He's really not that guy anymore and he hasn't been in awhile
Just one person's perception but Fitz has never been the A Johnson/ J Jones beast the media loves to cover.
Fitz has always been Fitz - a 6-3 "pretty darned fast" receiver who works tirelessly to perfect every aspect of his game. If there's one aspect of his play that stands out, it would have to be his consistency - play to play, game to game, year to year. At present, BA has Fitz running a lot of shorter routes (mostly inside) and when the ball comes his way, Fitz continues to be velcro.
I don't think Fitz has lost any of his speed or mojo. He's just used a little more conservatively. A more reasonable thing to be asking is: Will this next season be the one in which the gas begins to drain from the tank?
Personally I don't think so. Fitz keeps himself in good enough shape to stay productive for at least one (maybe more than a couple) more years.