Gronk apparently suffered through a strained achilles and a bulging disk this year, which made him look slow and he was clearly less effective in the passing game, though his blocking was still stellar.
By the end of the season, especially the SB, he was healthy, back to his jovial self, and pretty damn good in the SB in receiving as well as blocking. He's very smart with the money he has made and can definitely retire if he wants, to pick up acting or WWE or whatever the heck he wants to do with his life. He loves football, but it's hard to love football when you're hurt.
We'll have to wait and see.
I definitely think that if Gronk retires the Patriots will never win a single game again though. Yep. Definitely not.
Let's face it -- the Patriots will trade for one, or sign one, or whatever, and/or reallocate the money to pick up a strong WR or whatever. The ONE thing the Patriots under Belichick do is ADAPT. If you can name the TEs that helped the Patriots win the SB in 2001, 2003 and 2004, then good on you, but I bet most here can't.