Something interesting to note if we're theorizing about Saul's survival...
Vince Gilligan said that Saul is the only safe one, and compared him to a cockroach in that he may be disgusting as he is, but he will always be the one to get away and survive. However, in an interview after that, not too long ago, he said that the supposed spin-off TV show could very well be a prequel. Maybe he changed his mind... either way, I'm betting Saul lives.
I think Walt and Hank will kill each other or Hank actually arrests Walt. Skylar, Walt Jr....I have no idea, I think they may get away and that will be Walt's one redeeming point in the end is getting his family away and safe and he goes down in flames to facilitate the process of keeping the target on him. I've thought this for a while but it's looking less likely as the show has gone on with Walt and Skylar's relationship being nonexistent. I kind of hope for this, but doubt it'll happen. Jesse will die.
I've pictured the Saul show not unlike his interactions with others in scenes of the actual show, with new material and/or how he began his descent into being Gus' guy. So he'd probably be dealing with some crooked business and be doing shifty things as he does, it'll be him that is quirky and comedic. I think it could be really neat if done correctly and if they keep some of the macabre and serious scenes (just much less prevalent).