Let’s see…
From birth until last night’s scene with Chuck, he was “slipping” Jimmy McGill. And that’s who he was when the show started.
As he came to become valuable to HHM, he started becoming James McGill. His brother… did not want, nor believe, this.
As the stress of fighting his brother to achieve his validation heightened, James… the lawyer… started using the law in a way that slipping Jimmy would not: to destroy people.
To destroy his own brother.
It was the psychological need to flee from what he did to Chuck which caused the two elements… Jimmy and James… to merge to become Saul Goodman (the court house scene at, what, the end of season 4?). The Saul Goodman split-identity was his shield. The things which were done to his brother? Done by that other guy.
However, Saul Goodman was toxic to Kim. Kim could handle James McGill, that’s who she fell in love with. She thought she could handle Saul Goodman, but Saul was darker than she expected… and led her, internally, to places she never wanted to know lived in her heart.
He remains Saul from the courthouse “It’s all good, man” introduction to his disappearance in BB, headed up Omaha way. And because of his Saul life, he was forced to become Gene, manager of a Cinnabon.
He does this for a few months, totally and completely Gene.
Then, one day Gene comes home. He digs for boxes. He pulls out a VCR tape. Goes to the TV, puts the tape in the VHS player, sits down, and roll credits. This sequence literally opens up the first episode of season one.
The rest of BCS is Gene sitting in that chair, watching that tape, remembering That’s why the ‘weird’, short intros - they were the VCR takes. Some were highly focused, some out of focus, but those short intros were from the tape he was watching.
And, sitting in that chair, he reminisces about his Kim days.
We get to when Kim leaves. The tape ends at that time as well, which is why all the B&W Gene-in-Omaha episodes started showing the “Vince Gilligan” blue cue cards (which were common at the end of VHS tapes) in the opening “BCS” sequence.
That episode, when the tape ends, Gene gets up and decides he wants to be Saul Goodman again. He is sick of Gene. He is tired of this nothing existence. We’re done remembering our beautiful, colored, life, it’s now time to focus on escaping this grey death.
To get Kim back.
He scams the department store/security guard. Builds up some cash. Has to put some pressure on his cohorts because they’re stupid, also meets Carol Burnett.
He is still metamorphizing back into Saul Goodman when it all falls apart. He calls Kim. Finds out that Kim has repented in a way he will not, and learns that all of this was for nothing. He is never, ever, going to get her back.
So he goes crazy. Wants to get caught, even though he might not realize it himself. Goes to the cancer guys house, etc. However… he is not a killer. No matter what Saul Goodman is, he is not a direct killer.
Gets arrested (and I’m glad there wasn’t a miracle escape). He is fully Saul Goodman now, the situation requires it. Negotiates as Saul Goodman, had that 7 year deal set up, just wanted that ice cream…
And he finds it is all for naught. Kim has ethically trumped him again by turning herself in. He realizes that, even in 7 years, there is no future with Kim as long as he is unwilling to join her on her journey towards the light, just as… six years prior… she joined him on his journey towards darkness.
So, sitting on the plane, he finally realizes there is no conning his way back to Kim. He has to take the hit. He has to confess like she did. In 7 years, as Saul, he won’t be any closer to her than he is now.
But… as James? Yes, that’s still possible. It’s his only shot.
And so Saul pulls his last con… on himself. He gets everyone together, and confesses his sins, blowing up all aspects of his plea deal. He gets the max, he is going to die in prison, he may not even know if his plan worked. Saul has to kill himself so that James McGill… the man Kim loved… could live again.
And it worked. Kim came back.
… anyway, that’s how I read all this Jimmy/James/Saul/Gene stuff.