200 national Spideys & Captain America becomes Captain England/France/Turkey/China/Nigeria/Brazil each time he has to travel to a different country for a caper (We could have a Captain World Cup where they all compete against each other for Captain of the World).
Falcon becomes Eagle becomes Condor/Albatross depending on geography. You get the picture.
Its the multiverse within one universe.
We even have versions of nations undersea now (Wakanda et al) so there could be 2 of each country (maybe 3 with 1 version suspended in the air?) so 2 * superhero * country * all superheros * multiple universes = total no of superheroes.
By extension (whoever's left over can become mutants & ergo X-Men.) EVERYONE on earth's a Superhero! (Oprah's happy) How about that?!!