If Zaire is going to leave, he should leave now, but I see no upside for him in doing so. He's not guaranteed a starting role at a prominent school elsewhere.
Unless Zaire absolutely kills Spring and Fall camps, and he is unequivocally the king in the eyes of the players, he's unlikely to unseat Kizer.
So, he'll likely land as the preferred back-up... and will see the field in special and red zone situations. It's a good problem.
It seems Wimbush would be receptive to a soph RS as he was acknowledging that he'd likely have to RS as a frosh... unless he absolutely destroys the runner-up in the starting role.
Zaire's best bet is to soak as much as he can from Sanford, make the best of his plays, study hard and find a 5th year grad transfer.
If Kizer continues on his trajectory, he will leave after graduating in 2 years, then Wimbush has 1-2 years.
If smartly managed, ND should be able to keep them all... USC was able to do so with Leinart, Palmer and so on.