I've read a couple Bama boards, and the overwhelming stance is they trust in Saban to not do anything to jeopardize the team. The vast majority think the hiring is some validation that Sarkisian did not relapse and those rumors were inaccurate or overblown. General praise for the expected easy transition, and many feel he'll be an upgrade.
I was astounded at the nearly universal blind faith. Especially given the nature of the battle Sarkisian must wage for the rest of his life. Not to mention he reportedly could not even stay sober under Saban in his first few months there.