As much as I hate Yasuo, I don't think those buffs will make him broken, so don't freak out
Yasuo is receiving buffs to his MR because while his top lane winrate is solid, his mid lane winrate is... not as solid. (source: https://br.op.gg/champion/yasuo/statistics/top)
Those buffs are meant to help him against mages, but don't worry, they are not that big.
The ult buffs are meant to help him engage against the back line later in the game during the big fights, where he is already strong.
Also, remember that Riot already said that they will rework Yasuo so that he will be banned less often and be less frustrating to play against.