Nathan Ferguson has been playing for the U21's since 20th Feb. He is obviously being managed closely in his return to football from his latest injury but having watched quite a few u18 ands u21 Palace matches NF is a very classy player.
NF has played in 4 of the last 5 u21 matches, 45 mins on 20/2 against Man Utd. 63 mins on 27/2 against Spurs. 63 mins on 5/3 against Everton and 77 mins against Arsenal on 17/3.
So no he hasn't been written off and could still yet prove to be a very valuable signing for the club.

3 years mate, 3 years

Yep…and he’s injured, again!

He’s made one twenty minute substitute appearance for the first team in almost 3 years!

He cannot sustain a level where he remains injury free for long enough to gain proper match fitness. He breaks down virtually as soon as he starts to make a comeback. This is a recurring theme and he has missed far too much of what should’ve been his prime development stage. Sadly, I don;t think he will ever complete a full 90 minutes for the first team.

Ferguson now reported to be out for the rest of the season with a torn Hamstring

If that's correct, that's likely to be the last straw with him being out of contract at the end of the season.

Irrespective of Ferguson earning a tidy sum for not actually having played a game, for his own benefit in later life and the health issues attached to his ongoing injury problems, he ought seriously start to think about another profession. The club has done as much as it could to rehabilitate him but it is clear that it has reached the point that to offer him another contract would be extremely foolhardy.