Regarding future seasons and character arc, especially in Omaha, I think the writers kind of put themselves in a corner a bit. They always state, and it's observable in what they put out, that they have to be true to the characters and not necessarily aimed at extending a series or making everything end happy. Could Breaking Bad have gone on more seasons? Yes, most shows would have forced some way to extend a successful series - Gilligan and Sony and AMC were all OK with bringing it to a conclusion in a way that fit the characters, Walt was reckless and had committed serious crimes and couldn't run from the law forever. He ended up with heat on him and dying.
The Saul and Jimmy we know is not really a nice guy, he works people from all possible angles to benefit himself. He can manipulate old people to hate some sweet old lady, he can suggest in BB that maybe someone should be killed, he's OK with making a person who's really done nothing wrong feel responsible for the death of his brother. Saul gets involved in a drug syndicate and as a result goes in to hiding in Omaha. Could there be a Omaha based season? Sure, but the Omaha we've seen so far is not really watchable over an entire episode much less a season - he's paranoid, he's working in a mall, he's trapped and sad. He has no freedom and if he ever wants to spice his life up and get back "in the game" then he puts himself at risk for capture by the law or death by vengeful criminals. I can't really see these show creators/writers giving Jimmy a happy ending - and it's hard to say he deserves it. It was a pseudo happy ending for Walt - he righted a few wrongs, freed Jimmy, and was smiling with pride next to his equipment as he shuffled off the mortal coil. For Jimmy I could see something similar - refuses to be trapped, gets back into the game of manipulation for personal game, sees success at what he's good at, but then gets captured or killed but at least going out what seems to bring him joy.
If they go to a Omaha based season I would really like to see Jesse though - and I think he is a character who could have a happy ending and even be argued he deserves it. Saul and Walt were grown men who made adult choices to break bad - or give in to bad impulses there forever in Jimmy's case - and they reap what they sow. Jesse was a bit of a young loser and a low level distributor before Walt became involved, but Walt was a manipulative older influence who took Jesse on a ride through hell. Jesse had a girlfriend die in his bed, another girlfriend shot in front of him, felt forced to murder someone himself, was kept in a cage by insane criminals, etc - all as someone age 25 or less? I think barely out of HS when BB started. I'd like to see Gene go looking for him, find him, and Jesse be doing well and maybe taking up a few episodes with him - one of the few characters who could deserve some redemption.
