But now you look at things like the fact that Cena has been a good guy for over 15 years at this point and has pretty much also had the same gimmick for that time as well. For years internet fans have been begging the WWE to turn John Cena heel and allow the "franchise" of the company to not be a good guy for once. However, into his forties at this point the company has moved on from him and found their next "franchise" even though Roman is not on Cena's level it was time for him to be replaced. Even with this in mind it doesn't matter though that John will be able to turn heel at this point as he is part time player now and this makes it even tougher to flip him to the dark side.
Though there might be other ways at this point to be able to turn John heel it isn't extremely easy to turn heel a top star that has been a good guy. Keeping in mind the amount of members of the IWC that have been dreaming of Cena's heel turn I am not sure if at this point they'd care as much about the anticipated turn due to the ascension of Roman Reigns. At this point I think it is safe to assume that John will continue down the road of being the company guy until he leaves the WWE for Hollywood like many have before him.