If a patch does happen that changes the game balance, then we'll just have to deal. Although to be frank I don't expect that to happen since the only patch we've seen was to fix a bug that prevented Peach from being used in For Glory. Addressing balance issues I'm sure falls quite a bit further down on the list of priorities.
In TF2 (to use a completely unrelated game as an example), when balance changes happen in the middle of a competitive season they have no choice but to saddle up and move on. A few times the update has come through mere hours before a scheduled match, which is always funny to hear about when it happens. When new items are added, the convention is to ban them until the next season to ensure a level playing field since the mechanics of item acquisition in TF2 is somewhat RNG-based unless you want to pay real money.
How do DOTA/LOL manage it? IIRC they also get regular patches that muck around with balance, but I don't follow their scenes at all.