My two cents...

This question will be answered in about 12 months. Production is done at the end of this month and once dealers have sold their Hellcats in 2024, then the market will answer your question. I think they'll always have that "allure" of being the last of a breed.

As far as the non-Hellcat Chargers/Challengers, they may maintain their value a bit more than the usual depreciation, just because of their association with their higher-end models.

As far as the Demon variants, I don't see their value diminishing. Will their prices keep escalating like they have been? I wouldn't think so but, who knows?

Full disclosure, I have a 2016 Hellcat. It's not an investment to me, I bought it before the whole last-call frenzy started up.