In the Marvel Universe, as in this one, Cosmos would be science-driven, focused on finding our place in the observable universe; although the nature of the universe and the tools for that observation would obviously be radically expanded in the 616.
I assume it would still be hosted by Neil deGrasse Tyson, although there’d probably also be a weirdly nationalistic and belligerent Latverian version hosted by Dr. Doom.
Neil deGrasse Tyson is a DC Comics character, sadly.
I’d want Norrin Radd to host it, and instead of the CGI spaceship, he’s actually on his surfboard.
