My guess is he would look better playing in the right system for a bottom half team, as he did for us pressing high in that 4-2-4 type thing in the preseason. I used to think he'd be an interesting piece for a counter attacking team like Burnley, Palace (who really could use a mobile #10 which Lingard is in theory) or Newcastle but now I think he'd struggle in that sort of setup, might be better off for a team that presses a lot and isn't reliant on him to be the only creative type, like Brighton.
I do believe England caps and his age are enough to bring us back a surprisingly healthy fee. He should have been identified as not good enough by Mourinho or Ole and sold for 20M to some bottom half of the Prem team, that sort of fee could bring back a useful player from the Champo, or mid-table France, Germany or Spain.