I believe salvation is a misunderstood concept, even I have trouble with it, I think mainstream christianity is guilty of that misunderstanding.
I think UR people mostly understand that we're not saved from hell or any eternal destiny but we're saved from sin and the result of sin is death. Salvation is about wholeness and life, the life which is in Christ. Reconciliation with God is what gives us this life and this life makes us whole, free, healed, etc...
Spiritually, that is.
So if Satan is ever a being in need of reconciliation, then we can say he'll be saved, made whole, restored to whatever he was before.