While I wouldn't mind seeing it end up being Paul Bearer or the return of a masked Kane.. I present to you two negatives on why either would be back.
Paul Bearer: Last time I checked, his health wasn't exactly the greatest. Kane's heel turn is going to help him greatly, but allowing an over-weight, aging man who was and still is somewhat of a manager-like icon.. to return with or against Kane. Why?
Obviously Kane is furious that whoever this is, isn't 100% for being alive or dead and its driving him insane. So the question is, what does he want it to be? While he said on Raw he thinks he's dead, that doesn't really answer whether or not thats what Kane wants it to be. And once again, I find myself asking.. Why, why Paul Bearer? What can Paul do for Kane now? Short of bringing back an Undertaker v. Kane feud, I don't see a lot Paul can do for him.
Due to how Paul Bearer likely looks, a storyline revolving around Paul Bearer being Kane's manager is WAY out of the question. And a storyline revolving around Kane wanting his "Father" dead completely.. just doesn't seem like it'd be worth it.
Remasking: While the mask is symbolic, the overall question is will it cause us to forget the stupidness that Kane brought with him when he unmasked? Kane isn't Rey Mysterio. He doesn't wear multiple colored masks for all the children to go crazy for.
Kane's mask was apart of him, because of his debuting storyline of being horribly burnt in a fire. He unmasked and the moronic storyline of Kane's burns being a mental scar were completely stupid and destroyed any type of meaning the mask could've had.
So letting Kane return to the mask might give Glenn Jacobs another piece of merch. to sell, but I doubt it'll suddenly make everyone who's seen Kane without the mask suddenly forget what he looks like within a month or two.
Positives: Now then, while I'd love to see Paul Bearer return. I just don't have a positive for it other than to say, hes Paul Bearer.
The positive I do have, however, is that personally I feel returning Kane to a mask of some type would be a great thing. Not to attempt downgrading him back to his original self, but instead to evolve him into a different type of mask. Almost playing into a type of "serial killer" situation in which when he wears the mask, he isn't in control of himself. Now by all means that doesn't mean when hes mask-less that hes meant to be face.. but it does mean when he puts it on, he can't control what he does, and hes more unstoppable than before.
Final idea..
James Mitchell: If you want to restick Kane with a manager. Pick up the newly released free agent. Mitchell did wonders for Abyss. Hell, he even did a great job with Judas, and Judas sucked!
I believe Mitchell controlling Kane would be a great storyline, and it would be one that even Paul Bearer could return on later in time.. trying to get Kane to come to grips with being controlled.