I dont disagree that his skill set is unique. And in full flow he really can be a joy to watch.
But... Do we even need his skill set? What is it exactly?
He is not explicitly defensive enough to be a DM, but doesnt offer enough going forward to be an AM, so in the end is a player that often unbalances things IMO.
Strong as an ox, insanely good dribbler, damn near impossible to get the ball off of and pretty solid defensively.
And yet - doesnt do much for us going forward, lacks incision, holds the ball to long, lacks vision really, and doesnt offer goals/assists.
He is a very odd player. As much as I enjoy so much about him, he has always been kind of frustrating too.
I do wonder if we will be better off for letting him go, to be honest.
Put it this way, when a player is that unique, and impossible to replace as you say, then naturally there is no consistency in the team between when he does/doesnt play. Things change substantially, and his appearance record isnt reliable enough to build a team to suit him - nor does he offer enough to justify that IMHO.