Still there is no word on qualification. From what I heard, the United States of America (USA) will automatically qualify as the hosts. For the remaining 5 teams, there seems to be some disagreement between the IOC (International Olympic Committee) and the ICC (International Cricket Council). The former want a region-based qualifier tournament to determine the participants, while the latter want participants to be selected solely based on the ICC T20I rankings, which can be unfair to the associate teams.
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.