It would be intriguing to see such a thing. There were others of quite popular nature of a CROSSOVER.
Mortal Kombat VS. DC Universe & Marvel VS. Capcom Infinite
These two had quite a big highlight of such a CROSSOVER (the latter one suggest further future versions along the series line). If there was Marvel VS. DC game, who knows what origin could be used to play it out?
Well that's all from me, looking forward to if such a day ever comes...