Yeah, I kinda think cloning a game completely and rolling it out as your puts you in a place where you might get asked to stop (though I doubt it would end up in sueing since the company would get pretty bad press for sueing some hobbiest who essentially is part of their target audience).
I do know for a fact though that at least a few games company don’t have huge issues with your using their older games resources (sprites etc) to build different types of games. Team 17 mentioned before would be a good example of thins type of thing - they’ve actually in the past been very positive about indie games of this type. As you say, the companies themselfs might well be rebuilding old game concepts into new casual games which makes good business sense - but with their evident artistic resources and the improvement in technology I’d expect them generally to create new art/sound/music for their new version.
Nintendo would be the biggest rip I think - a lot of hobby developers “borrow” some sprites from then now and again. How many zelda graphics based RPGs have I seen! I’m not sure I’ve ever heard of the big N even questioning it - let alone sending a cease letter - let alone sueing.
Whether it’s morally right to do it or not - entrirely different matter and enitrely subjective.