Reigns is fine, y'all have to stop taking losses out of context. Yeah he lost to Shane, but we all understand that it was because of interference.
But no he doesn't need to be reestablished, best bet is to use him like 2nd run HBK. He just had a 2nd run in with leukemia, you don't make him the guy with that baggage. Keep him as a guy that can use his status to gatekeep the main event.
Um you want to old man Cena him because of his leukemia? I don't know what the chances of his leukemia coming back again is but I feel like it's less than the chances of Bryan getting another concussion and they had no problem with putting him back in the main event.
I'm pretty sure every main eventer since the AE has missed big chunks of time with injuries multiple times, of course cancer is more serious than any of their injuries, I don't want to minimize that, but from a business standpoint losing a main eventer during a big push has always been a part WWE because how hard they work their guys.
I guess I just don't see pushing Reigns being that big of a risk, he went 11 years in remission the first time. Even if worst came to worst, and his leukemia came back during a championship reign, he could drop the title in a quick match, put over somebody big for squashing Reigns, and then quietly disappear to focus on his treatment.