This will not affect the entire universe, methinks. Marvel & DC have done dramatic changes before. They never last for very long before reverting back to the norm.
It is also as fresh start and gives the reader an overview of a what if situation. I remember them doing this to Batman, Superman, Thor (When Blake became Thor, not Thor himself) & even Spider-Man if I recall! Look forward to picking up the new Thor and seeing how it does. Even the Captain America one sounds great. Yes they should have more African American heroes. Not necessarily taking over past roles as such but there are more than Falcon needed.