We need to get rid of him, Denis and Samper in January, and also Rafinha and Munir if possible. Time to trim the squad and give EV no excuses not to use players like Alena and Malcom more, you know the ones who deserve to be here and can actually contribute something.
We won't get anything for Vermaelen in January especially with him being injured again now that transfer window will open. The only way to get "rid of him" is by terminating his contract but if we'll do that we'll have to pay out the rest of his contract. And if we're already paying him it's better to keep him until summer and see if he'll actually stay healthy and could play in some games. He's still a good player when fit.
Rafinha is out for the season and not going anywhere.
If Samper will ever be fit to play I would rescind his contract and let him find himself a club where he can get back on track but as long as he's injured we can't just release him.
We should've sold Munir last summer when he was coming off a good season at Alaves and his value was higher so maybe we could get around 8-10M for him but now is too late. He can start to negotiate with other clubs in two weeks. Betis apparently wants him if they'll sell Sanabria or Leon but we won't get more than a few millions for him if at all. If they want him on loan then I'd prefer to just keep him and give him minutes in Copa and some La Liga games to rest Suarez.
Denis is the most likely to leave.