His attitude is worth watching. He's been great, but lots of "troubled" guys - him included - have history of starting off good and turning sour by the end. One big factor in that is contract status. His contract was set up to really be a year to year thing but obviously that was the best deal he could get. Coming off a good season, what if he wants to lock in security now? What if he doesn't want to have his status hung up on a year to year contract. We like to think he could be better next year with another season back from injury, but age could also overrule it. Or he could even get hurt again and he has no security against it. He might want to parlay this year into some security and if you bring him back on a 1 year deal where he feels lower production will stop him from getting paid again he could be more prickly next year. That's pretty much what happened with Moss at the end of his time here, for example.
I'd be very surprised if he sees the end of his current contract as-is. It will either be extender/altered or he'll be cut after year 2 IMO. I definitely see him back next year though.