I would also be disappointed if this were the case. I personally just think the silver vs amber eyes just represent his turn to darkness rather than being influenced by someone else who’s even stronger. The only way I’d be cool with that plot element would be if it were introduced in a flashback,and kept there. Let’s say it takes place in the same period where we see that chess game between Xehanort and Eraqus in the first Tangled trailer. I just wouldn’t really want to see that used out of nowhere for the ending or as hype for a sequel. It would remind me of where near the end of Naruto you think Madara is the main threat until he gets plot twisted into being a pawn for something even stronger that’s the set up for Boruto. My point is,I just want some sense of finality with 3,and I feel like the inclusion of that would just be set up for later entries