Over at PFF, they profile Johnson's career so far in detail, giving an insight into what he might still be capable of. Here's part of their conclusion:
If Johnson’s breakaway ability is declining, then the smart play would appear to be pairing him with a powerful runner to wear the opposition down, bringing Johnson in when they are tired and more likely to make a mistake. Not an unreasonable thought process, but the question becomes how much does Johnson rely on those poor plays by opposing defenses?
Multiple sources continue to claim that the Jets are "interested" in Johnson "at the right price", but it remains to be seen whether they will make a move for him.