[RoboChair]

Just find a way to get everybody in Districts.

Everybody gets to do 2 events or more.
Those that do well in their 2 events get to have a local championship experience.
Those that do well at District Champs get to go to the World Championship to compete with the top teams.
FIRST has complete control over attendance numbers by saying "we will take X number or % of teams from each District" (more or less how it works now anyway).

Major issues currently

International teams would need a large enough team density to make Districts work for them(not easy).
The other option is to retain the existing International Regionals and add another few and the international teams stay regional based.
Alternatively give the international teams the option to compete at a district event as if it was a regional or compete in a district of their choice.