Not so sure about that last sentence, from his first Interview I've felt Nisbet genuinely has some affection for the Dons and I think that will have grown. I also think he is very career focused now, he was talking in his last RTV interview about how much better he is looking after himself, and playing for Aberdeen got him back in the Scotland squad. I think he will want to stay unless a better career opportunity (and I've no idea what that looks like btw but I know it ain't Millwall) comes up not a salary 2bh.
If we could get him for 750 k that would be a bargain I would say. He's only just turned 28 and we could easily get 4 good seasons out of him..... probably more given he's never been a player that has relied on pace.