I don't want Seve to leave for a number of reasons, mainly though because he is a good player and I would like to keep players like him at the club.
As has been said we will "survive" the loss of good players as good players will always want to play for Aberdeen. I also think replacing players is definitely advantaged by having Calderwood and Miller to sell them the club as well as the other good players we have at the club (Seve, Miller, Kerr, Zander, Smith, Aluko etc).
I don't "fear" losing players, I'd just rather we didn't have to every season.