Thoughts on an MMORPG that will (probably) never be

My semi-random train of thought started wandering back to Dream Park lately. If you're not familiar, it was a setting/series of books by Niven and...? Anyway, it was basically a huge sort of LARP theme park with crazy effects and such where several "games" went on at once and...honestly I can't do justice to how batshit the idea was for its time. The concept is pretty much superceded by "virtual spaces" such as, well, take a guess.

Anyway, there was a pen-and-paper RPG for it once. It did some interesting stuff with modular character design where there was a "core" that would be portable to all "settings", and "setting" or genre specific parts that only mattered in certain "settings". R Talsorian did it IIRC.

So where my brain was going was...what if there was an engine that could support something like this? Where you had a "core" character that could hop between settings/worlds, and had a different roster of setting-specific abilities in each one (which might or might not overlap in some cases). There's more to it that I'm too tired right now to go over in detail. Anyway, I wonder if there's a modern engine that could support such craziness? Or would someone have to cook something up that could handle it?

Just random thinking. Probably a thing that will never be, but sometimes it's fun to imagine.