I'd rather keep him purely as he meets the homegrown quota and is reportedly on relatively low wages and less than all of our other midfield options I believe. That isn't ample reason of course, as having the best quality at your disposal is the main issue, but I do think he can prove a more useful asset to the team that than of Fellaini, Fletcher and most certainly Anderson.
Carrick and Herrera are out of the equation, as the former is our only reliable midfielder - in my eyes, despite last season - pre-Herrera and the latter is a quality, new acquisition. If we look to offload Fellaini, we could still recoup a sizable fee, perhaps half of what we paid, as he can still be a dangerous weapon for someone teams, but he simply isn't a central midfielder. In regards to Fletcher, he has lost the key traits which more or less made him the player he is, but it could be a bit pointless offloading him when he isn't on high earnings, wouldn't fetch for much and we are sorely lacking leaders and senior players as it is.
Back on topic, I do believe Cleverley can be revitalised here. I never thought he was capable of becoming an excellent player even when he broke out into the United first team a few years ago, as he simply doesn't have any remarkable aspects to his game. However, he is a player shattered mentally, unable and unwilling to express himself fully on the pitch in the last few years and someone who could thrive in a team player at a faster tempo and relying on plenty of movement. If playing alongside the likes of Herrera, Mata and Kagawa can't revive his game to the best of his abilities in that respect, nothing will.
Sell Fellaini & Anderson. Keep Fletcher and Cleverley. Add another midfielder (Vidal hopefully) and then assess our midfield on January when Strootman might have recovered and become a realistic target.