I very much doubt The Rock has any interest in taking that belt or doing a second match with Roman to put him over. I also very much doubt the company ends a near four year title reign with a 50+ year old man who will be gone the next day.
It'll take a serious injury or the crowd badly turning on Cody for them to divert from Cody winning the belt. (Even if it's not at Mania 40) People keep talking about LA Knight, but I think Triple H is smart enough not to hot-shot that.
As for claim as the "Tribal Chief", don't see Rock going over Roman for that either. IF they ever decided to make the "Tribal Chief" a moniker to be fought over, the obvious choice to go over Roman would be Solo.
Not sure I even see them doing that, though. To me, all the company has to do is make Roman go away for 3-4 months, return, and play the same cocky character he is now, but as a dick to heels rather than faces. They'll be printing money selling tickets and T-shirts with him as a babyface Tribal Chief, so long as he's not smiling, shaking hands, and kissing babies.
But maybe there's a story there, too. Solo goes over Roman and claims to be the Tribal Chief. Roman goes away for awhile, comes back, and goes on a run as a babyface to reclaim his "Title". Gives a year to establish Solo as a dominant heel main event character, gives Roman a redemption angle to chase something other than a belt, and sets up a massive face run for Roman.
tl;dr - Rock's not taking the belt off Roman. Cody probably still is. Roman still should have a big babyface run ahead of him as the same exact character.