Why is Riot buffing Cho'Gath?
He is one of the champions which I think that least needs buffs. He is already strong as he is now. The only reason why Cho'Gath is no longer popular is because of meta changes; Cho'Gath is countered by juggernauts, by Sated Devourer champions, and assassins aren't exactly popular so his ability to counter assassins is not in demand.
But Cho'Gath is still a very solid choice, he is ridiculously strong. His burst is massive and he is very tanky even if he builds full AP. I don't know why Riot is buffing Cho. There are so many champions that needs buffs more than him, for example: Kha'Zix needs buffs, Fiddlesticks needs buffs, Twitch needs buffs... Cho'Gath? He doesn't need buffs.
On my opinion Cho'Gath is balanced. However, the only reason why he is balanced is because he is immobile, easy to kite, and requires to land his Q to be able to do anything. He is bordeline OP and any buffs that he receives will make him go from balanced to broken.
He is already strong and I fear that if these buffs go to live and Cho'Gath proves to be broken, instead of reverting the buffs, Riot will change his other abilities and gut Cho'Gath.