Speaking of the landing the plane metaphor, the airline that Jimmy and the Marshal flew back on was Wayfarer Airlines. The same company that went down in the 737 Down over ABQ episode in BB.
The scene in the prison with them smoking? A beautiful callback.
Jimmy got what he deserved, and more importantly, came to understand that he needed to take accountability for what he did. He finally shook off his Saul and Gene personas, and embraced being Jimmy McGill. Sure, he'll probably be a popular inmate in prison and no doubt offer some legal advice, but he knows that he's there until the end and he accepts that.
Unlike Walter, who went to his grave forever convinced that he was right and everybody else did him wrong.