We would be absolute idiots to let him leave for very little or free. No chance at all.
If we don’t get a ridiculously high offer, he will go on loan. Mark my words.
The issue is with the loan, is it puts us in the exact same scenario next summer.
In order to get a good price on a sale, you must have a credible threat of keeping the player if you don't get a satisfactory offer. We've destroyed all our leverage by announcing that he's never playing for us again, we should have started the sale process early in the summer whilst briefing that we may integrate him back into the squad if our valuation isn't met. Obviously we'd have no actual intention of ever keeping him, but it would have put us in much better negotiating position.
If we get lucky and there's multiple offers from different clubs then the bidding war may end up getting us a half decent fee, but it won't be anywhere near what he was worth 18 months ago.
At this point you just have to treat any money we get as a bonus, we were all preparing to lose him for nothing for the last 18 months.