Yeah I mean like… a full on conversion at the level of Fallout London or something like that, but with access to more ‘guts’ of the engine… done by pros?

Yeah, I’d bet Obsidian can do something like that, at the least, and it would be broadly better than FO4, again at the least.

Also my absolute random bet for FO5/ES6 will be radiant enemies along the line of Spore creatures, hahahah!