Having a defined high tier in a game, even one that shuts off some other characters' options completely, doesn't spell doom for any particular FG. Melee has been out for 12 years and had a strong showing at EVO, despite having a ridiculously tilted tier list (try winning a tournament without using fox, falco, peach, marth, or shiek). There are a TON of "Kanos" in that game, and a bunch of characters who might make it out of pools but get bodied hard by competent top tier. The community never banned Fox. It accepted the game for what it was and kept playing (for a very long time, and still do).
My point here is that the life of a FG rests solely on its community and not making tweaks to cater to those who would 'only play the game again' if something fundamentally were altered by force. MK might not be at the next EVO, but it's on all of us to keep hosting tournaments and keeping the game alive - I'm not sold a character ban, even a temporary one, would increase showing. Maybe I'm biased because I don't know how hard that MU is for a lot of chars (it's honestly not awful for Reptile). I've played competent Kabals, but not someone on REO's level.
After all of the salt, Kabal has never won an EVO, but even if he did, I'm not sure it would change things. The truth is that watching high level Kabal play is entertaining. The last 2 EVO grand finals were both very fun to watch (all 3 were, actually). I don't think that Kabal takes away from the hype or makes the game degenerate.