He got himself in a snake pit.
First he has to arrive in perfect shape, which is doubtful.
He's got to perform at the level he did 2 years ago, which I don't see possible just because this is a whole different team (Only STAT left, as a matter of fact) and a whole different system (ball is in Melo's hands)
The comparisons with Lin will be inevitable, not only Felton will not come near the level of Linsanity (which is unfair, but will be brought up), but baring an injury, Lin will put insane numbers in Houston (it's his team and his team only).
And if (when) the Knicks start to underperform, the pressure will be huge on all the players, specially Carmelo (unless he's carying the team somehow) and secondly on Felton.
Those are the reasons why I'm not very optimistic right now.
It takes a very tough (dumb) guy to take on this challenge. Some people say Felton has the personality, but when we're talking about a guy who tanked the whole last season and got to 30 pounds overweight, I think it's just fair to question his drive and professionalism.