He has to until his reign ends at least. Imagine if he only shows up once a month as the WWE champion, not going to happen, the whole show evolves around that championship and the fueds involved for it.
No, the whole show revolves around Cena. The WWE title is the mid card title as long as CM Cunt has it.
Rock won't be doing house shows, either, don't kid yourselves. He wouldn't be the first champion not to (Goldberg, Shawn)