Don't know what else there is for him to do. He's too slow and predictable outwide vs literally ANY athletic WB and would struggle vs Vazquez or Roberto. He's close to Isco levels of pace. In middle at least he can do an occasional flick and flamboyant play. If he's the guy you get the ball to in the center he can still get away and create a counter for faster mates. Can still do his thing of using balance to escape tackles. At this point I don't see any other role for him. He definitely can't play from a static ball and take on a guy bigger/faster than he is anymore.
But maybe I'm overdramatic. Just kinda telling that even Ancelotti seems to flat out say "yes, Vini is undisputed LW" and then goes on and implies "hm I thought of using him but the 20 year old seems a better choice" at RW vs toughest group opponent away