I think you and DevDogAZ see it the way I see it. Jimmy still couldn't help but use his skills to work a deal, just because he could, but he didn't really care about 7 years vs. the rest of his life without Kim, or at least Kim's approval. Even approval is a bit strong...maybe acceptance? He did it because he knew what HE could live with was pretty horrible, he wanted to be someone SHE could live with (not cohabitate, but tolerate).I really liked the ending. I think that the character of Jimmy was complex, he was a hard worker, he wanted to help his elderly clients, he loved Kim, he loved his brother, etc. But as he started losing the things that were important to him ( like his brother and Kim), he turned into Saul, a character whose only real love was for money. To the point that by the time he met up with WW, it was all Saul, Jimmy was gone. Then in the ending, his confession in court showed that Jimmy was still there, that he had regrets, and the only way he felt he could save Jimmy from Saul was to confess his wrong doing, and ask for forgiveness. Not from the judge, but from Kim.
As for the prison sentence, I think that the 86 years is actually pretty light sentence for the crimes he committed and admitted in court. If I am reading things correctly, the federal penalty for conspiracy to commit murder is up to life. And he admitted to conspiracy to kill Hank and his partner. If the feds had really thrown the book at Saul, he would be facing dozens of life sentences. Plus, those are federal charges, I'm sure that if the feds could only lock him up for 7 years, the state of New Mexico would have been able to dig up some more charges to pin on Saul without double jeopardy. So all in all, I think that Saul got Jimmy a pretty good deal.
I also have to wonder what Jimmy would do if he got out in 7 years with no law license, all his criminal buddies long dead, no Kim, no brother, he has a degree of fame for being a conman, and no more Cinnabon. I doubt life outside of prison is going to be much more enjoyable for Jimmy then life in prison where he at least seems to be respected by his fellow inmates and his legal advice is valued.
And when they shared their last cigarette, didn't the overhead light have that same odd angle on the as it did in the garage?