So what if General Motors didn't cease production of the Chevrolet Caprice?
The fourth generation Chevrolet Caprice Classic (1991-1996) marked the end of one of the last "true" American full size land yachts built by General Motors' Chevrolet division by Americans for Americans before the introduction of the fifth generation and sixth generation Holden Caprices, which were built by Holden, which is basically General Motors but in Australia, for the 2000-2005 model years and 2006-2017 model years. It's sad that a car model that was born in America ended up dying in Australia honestly. But look at it this way, don't fix what isn't broken, when the fourth generation Caprice was introduced during the 1991 promotional commercial, it was slightly outdated as full size cars weren't a hot seller anymore and it was aimed at grandparents who likely had the older generations when they were younger (ex. Robert Sterling said that he was retired and engineer Brian Borg said, "for those of you with grandchildren, you know sooner or later there going to spill their soft drinks on the seats..."), so at least the Caprice model name wasn't ruined or made worst by General Motors, rather Holden takes that responsibly unfortunately. Though some may argue that the third generation Caprice was the last best one. Rip Chevrolet Caprice (1966-2017).
Honestly, had General Motors not converted two of their plants which produced their b-body platform cars in favor of their SUVs, I can guarantee you that the fourth generation Chevrolet Caprice Classic (a.k.a. the bubble Caprice or a beach whale) would've lasted longer than from the 1991-1996 (basically 6 years) model years, as the previous third generation Chevrolet Caprice lasted over 13 years (1977-1990), which was long over due for an upgrade (technically the fourth generation Chevrolet Caprice is basically a third generation Chevrolet Caprice as they both share the same exact body on frame chassis, primarily more updated in the interior and exterior), as I can envision GM bringing the fourth generation out as soon as the 1987-1989ish model years in an alternative universe and lasting to probably close to around the late '90s or early 2000s. Chances are that the b-body platform, much like Ford's panther platform (ex. Ford Crown Victoria, Mercury Grand Marquis, Lincoln Town Car, and Mercury Marauder), consisting of the Cadillac Fleetwood, Buick Roadmaster, Chevrolet Impala SS (and nobody seems to care about the Oldsmobile Custom Cruiser) would've all probably still have been around together longer much like Ford's panther platform did. And very well could've out competed Ford's second generation Ford Crown Victoria fleet sales, which was introduced for the 1998 model years, as Chevrolet Caprice's (9C1 police interceptors in particular) were more popular and cheaper to buy than second generation Ford Crown Victorias (P71 police interceptors in particular) for many police departments, and would've very well have kept General Motors in the league for fleet vehicle sales for years to come, not handing the police market directly to Ford.
I know for a fact that law enforcement would still have used them as police fleet vehicles (ex. Jumanji (1995)), taxi's (ex. Geto Boyz's Mind Playin' Tricks on Me music video (1991)), Outbreak (1995) and Godzilla (1998)), fire department vehicles (ex. Daft Punk's Burnin' music video (1997)), station wagon funeral coaches, government cars for ICE and the FBI (ex. The Matrix (1999)), security cars, etc.
Had the fourth generation Chevrolet Caprice lasted past the 1996 model year, maybe there would've been another facelift just like for the 1993 and 1995 model years, perhaps for the 1997 and 1999 model years, assuming they kept the same design every two years like they did and still kept good quality control, as the fourth generation Chevrolet Caprice was overall a reliable car, though a gas hog in the city, with few minor issues. Since the Chevrolet Caprice is an entrance level luxury car, perhaps General Motors could've given it; a better cup holder, a floor mounted gear shifter for civilian versions much like the seventh generation Chevrolet Impalas, maybe a better transmission to better work on par with the stronger engines (as the 4L60E transmissions, as well as its 4L65E transmission successor, generally lasted well into the 100,000-150,000 mile ranges, whereas the stronger 4.3L L99 V8 and/or 5.7L V8 LT1 engines lasted well into the 350,000-400,000 mile ranges), maybe put a gas cap on the driver side for safety reasons, add a daytime running light (DRL) sensor to dim when it's bright outside and put higher beams on when it's dark outside, CD players could've been standard (as the Delco/Bose CD player was an extra option as far back as 1991, but there's always third party cassette to CD adapters or FM transmitters for Bluetooth connectivity), made the blinkers blink slightly faster, have added a small yellow rear blinker tail light instead of having the entire red portion of the tail light blink, maybe could've added a radio antenna that could go up and down when in use or not respectively, have added fog lights on the front bumper, reflective plastics on the rear bumper, given their Chevrolet Caprice 9C1 police interceptors black grilles instead of chrome (much like Ford Crown Victoria P71 police interceptors compared to their respective civilian ones), have fixed common electrical problems like the faluty fuel guage problem and faulty theromostat, repositioned the optik spark/distributor cap to not break easily from puddles of water, put a better oil pipe design, a better fuel injection system for more MPG on LT1 engine versions (for better fuel efficiency, as LT1 engines were for performance and of all the b-bodies, only the Chevrolet Caprice had the L99 engines for fuel efficiency), fixed the exhaust manifold bolts from breaking easily, gotten rid of the anti theft key and introduced only a key fob for opening up all four doors (as there was an optional fob for opening just the trunk) and trunk too, gotten rid of the fender skirts from the station wagon (since it should've been done starting with the 1994 model year because the third generation Chevrolet Caprice station wagon never had fender skirts, so it's not impossible), or probably have gotten rid of station wagons as whole and focused solely on Caprice sedans, had four disc rotors, maybe have gone down the Ford route and assembled them in Canada (as Canada generally has good quality control), maybe introduced a third airbag for the center bucket seat rider, etc.
But when the 9/11 attacks happened, fuel prices started to rise slighty after the war in Afghanistan and Iraq, so that would've definitely put a strain on sales, forcing the next fifth generation to happen as soon as possible in the name of fuel efficiency, as cilivian people's economic reach would dwindle in uncertainty to continue to keep such a car when used primarily in the city. Though the Los Angeles Police Department (LAPD) didn't officially retire the fourth generation Chevrolet Caprice (9C1 police interceptor car) until 2008, which by then were likely just the 1996 models, so assuming the fourth generation lasted longer, they would've retired the final Chevrolet Caprices until at least the early to mid 2010s. And the 2008 recession almost left GM completely bankrupt in 2009, so higher fleet sales from 1997-early 2000s would've definitely helped, even if they went the Ford route and ended civilian production of the Ford Crown Victoria in 2008 and just produced the Chevrolet Caprice as fleet vehicles from 1997 to the later late '90s or early 2000s.
General Motors did have plans to resurface the Caprice model name in America for the 2000 model year, so if Holden wouldn't have taken the model name, the fifth generation Chevrolet Caprice made by General Motors (not Holden) would've likely debuted in the early 2000s, and in my opinion likely would've ended up looking the same or like a mix between a eighth generation Chevrolet Impala and a first generation Cadillac CTS, which would look kind of horrible, but GM is known to have mediocre designers, so you never know. And it very likely wouldn't be on a body on frame design anymore, probably would've been available in rear wheel drive and/or front wheel drive configurations, featured a detuned Chevrolet Corvette (C6) 6.2 LS1 engine for more HP, had a heads up display (HUD) as an option, etc., but it's safe to say that it likely wouldn't be the same full size sedan that the previous fourth generation was (but rather full size in today's terms much like a Ford Taurus or Dodge Charger), very likely killing fleet sales for police and taxis especially with more cramped up interior space. It's currently July 5, 2020, but if the Chevrolet Caprice make and model still existed, it'd probably look like a tenth generation Chevrolet Impala in my opinion, which would just be sad.