Keep it, future classic.
The future of vehicles is increasingly electric, boring, stale, and computer dominated. Sure there will be companies like Rivian who will try to keep the enthusiast spirit alive but those brands and vehicles will be fewer and farther between. For now though, I'm happily enjoying some of the last great ICE's made.
Resale value might be high for now but (for me at least) you'd never get the same enjoyment value out of another vehicle because there's no other vehicle that can do what these trucks do.