It is a pity that he's a shadow of his former self as he was fantastic to watch at his best.
Some riders have ridden on too long (Peter Collins for example) and left a slightly watered down legacy as a result.
Mark will know when he's had enough, i'm sure observations from the likes of me will have little bearing on that decision.
He's still scoring at a decent 2nd/3rd Heat leader level, but to tout him for a GP place is plain daft and would do him no favours at all.