A suggestion that I've done virtually zero strategizing or poking at to see if viable...
If we want a 32 team playoff for the ultimate resolution of a Champs Season. What about:
Top player from each race qualifies (24).
Second best from each race qualifies (24 more).
Creates a field of 48 teams
Top 16 players get a first round bye.
Round one is 32 players, yielding 16 winners.
Those 16 winners then face the top 16 off their bye week (giving them a reward for being in the top 16, regardless of race, that refreshes any MNGs they might have had from the final game of the ladder).
If you really wanted to get tricky - you could even make the two 2 fling/gobbo teams play play each other in that first round to ensure two stunty teams advance to round two (if you were a person who cared about that for some reason... I am not) - this assumes that neither flings/gobbos would be cracking the top 16, which i expect would always be the case. but who knows?
This allows for equal representation from each race, but also makes the top 16 coaches feel like maybe their grinding efforts are somewhat more rewarded with the first round by (that doesnt absolve them from still needing to win the same number of games to take the pot as they currently would).
The other, more unlikely, suggestion I'd have is that you (Cyanide) produce a really awesome custom kit for every race that you can only earn by qualifying with that team. That will be enough of a draw for some of the regulars, I expect, to mix it up every season to try to unlock the kit on additional teams. But yeah. That requires extra art time, and whatnot. So I expect that's a nonstarter right now.