It can be unfair to the associate teams for sure, but profit is their primary motive and that would only be possible through a competition between the best of the best T20 teams based on the ICC rankings.
I am guessing that USA, India, Australia, England, West Indies, South Africa and New Zealand would be the ones to participate in that tournament.
If profit is the primary motive, then in place of New Zealand it is going to be Pakistan. Also, West Indies can't compete as such. They are a group of around two dozen different independent countries and dependent territories. In Olympics most of them compete separately, and therefore it will be impossible to have a West Indies team in the Games. Only 5 full members will be allowed to take part, and IMO they will be: India, Pakistan, Australia, South Africa and United Kingdom.