His price will drop like a stone if he has not played for 6 months, and clubs know he wants out and you need to sell, in the case you mentioned you would be lucky to recoup your original price for him. Hell even now after he has made it public he wants out and after one of the best seasons of his life there is still only one club in for him, 6 months out doing nothing and the price will plummet.
As I said We'll see.
The only thing you added to an already existing list was "hadn't played for 6 months which isn't true. It will be 4 and only if he goes on strike. He'll still be the same player he was. He's not recovering from a big injury and I doubt he'll live in Burger King in World Cup year.
But If that's the case it works both ways: so will any chance of improving on his current salary in fact he'll be offered less and he's in it for him after all. These imaginary ultimatums are a double edged sword after all.