I just realized a little thing:
If I see this right, angels can only "possess" humans with special blood, like Jimmy, and, per inheritance, his daughter. Lucifer is a fallen angel. Sam has special blood. Maybe different special, but maybe not so much. Does that mean that if Lucifer rises, he'll do it through Sam? He could, of course, find other people with special angel blood, too, but that wouldn't be as dramatic. I'm also sure that Lucifer isn't the type to ask before he possesses, and that the tattoos might work against demons but not (fallen) angels. I'm scared now.
I stopped the avi once the "Soon" came up, by the way, so I'm unspoiled for the rest of the season! Or, I'm not sure. I think I read the title of the last episode somewhere, but I could be wrong. I certainly won't go and check!