I also suspect all attempts to keep doing combustion engines for mainstream driving are going to get gradually overtaken and lapped by BEVs.
Chrysler flamboyantly gave this back burner project up and promised to halt further development as part of the wrangling around the government loan they got to save them from bankruptcy in 1979.
Basically it was a song and dance to win political points among the same generation of absolute genius environmentalist who thought moving a steel mill from Ohio where you can regulated it to China where you can't is a win.
I suspect that had the project died a natural death in the 80s rather than being publicly executed as a warning we likely would see some trickle of development these days since they see like a nice natural pairing for various sorts of EVs and CVT powertrains.
It's also worth noting the degree to which facilities and talent pool overlapped between Chrysler, Chrysler Defense, how much more porous the corporate world was 50yr ago and that that Chrysler did ultimately get someone else's turbine into a running driving mass production vehicles in the form of the M1 Abrams so it's not like the technology is unsuitable on a fundamental level.
You can extract more energy by adding stages but that increases weight.
While a small and light weight diesel engine is already very close to the theoretical limit.
Turbines for land uses have heat exchangers to get a lot of this back. Even after those the turbine is still lighter for a given power output and lifetime. But normal engines are a lot cheaper.