There is already an easy solution to this problem you just simply follow the structure set forth by FIBA
https://en.wikipedia.org/wiki/FIBA in the real world. Everyone keeps there own national identity, drafts players of there own country but compete in leagues that consist of
Africa
https://en.wikipedia.org/wiki/FIBA_Africa, Americas
https://en.wikipedia.org/wiki/FIBA_Americas,Asia
https://en.wikipedia.org/wiki/FIBA_Asia,Europe
https://en.wikipedia.org/wiki/FIBA_Europe, and Oceania
https://en.wikipedia.org/wiki/FIBA_Oceania.
The cream will rise to the top of the continental leagues and you lose no NT effects as each country maintains its NT identity.
I dont think the NT matters at all to most micro nations, the only select voices we hear are the ones who have vested interests in competing against bots while turning over large profits.
Im interested in how many Supporters are there in Micronations?
An exact number isnt needed but, id be interested to hear a guestimate.
Oh and for any person who plays this game that feels like they couldnt play with someone simply because they are from another country the world doesnt need you. It's 2016, Grow up and be an adult, we all bleed red. Get over yourself and you will probably find your life far more satisfying