Absolutely, monster gimmicks can only go so far. For the performer to move on and progress, he needs to start incorporating more and more realistic aspects to his character. Picture the Undertaker or Mankind if their characters never evolved from their initial incarnations. It would of gone stale, and these are two of the best of their generation.
I always go back to this match shortly after WM 32 where they had Bray tag with Reigns. You could tell at this point it was time to start removing the more hooky and theatrical elements of Wyatt's character and become more real. Look at the reaction he gets at the end when he hits his finisher on Del Rio and then points to Sheamus as Reigns spears him. The crowd was ready for more Wyatt and less swamp-man goofiness. Yet the WWE ignored it and he got so stale to the point where he needed to be re-packaged 6-7 years later.
I don't know how far you can take this Friend gimmick. To me, it's even harder to have this version of Wyatt evolve into a more realistic character, which he will need to do to stay relevant long-term. Even his entrance, as great as it is, will wear thin after folks see it a bunch of times. And to tell a story through feud, how many times can you have the Fiend ambush his rival in the ring before it goes stale too. I give them credit for coming up with something fairly original, but wonder if ultimately this character hand-cuffs a very well-rounded performer in Wyatt from becoming as big of a star as he can be.