There is no reason for there to be more than 16. Teams should need to prove themselves if they want to attend international tournaments.
Also, 16 is the perfect number for groups. It's a square number divisible by 4, setting up GSL really nicely. When you extend it to 24 GSL or 24 Swiss, teams are really burnt out in the end. CS:GO uses Bo1 to eliminate that, but I think Bo1 in international events for VALORANT is horrible.
Not only is there player burnout, you have to deal with viewer burnout: I personally am really bored of VALORANT at the end of Masters/Champions tournament.