My guess is he uses that big ass gun from his car, kills the guys holding Jesse, tells him he is sorry and free's him. Kills the Nazi's because they killed Hank but doesn't kill Jesse.
Then the Ricin he is uses on himself or they end the show with him in a room holding the Ricin and we never know if he uses it or not.
Are we watching the same show? In Walt's mind Jesse is the reason Hank is dead. He put a contract on Jesse's head and then told him how he watched Jane die for the sole purpose of inflicting emotional pain. There has been no indication whatsoever that Walt is the least bit interested in anything other than revenge. It's fun to speculate and all but c'mon man.
I would be floored if the writers had Walt do a 180 on Jesse. It would make no sense and be totally out of character. Jesse snitched on him which led to Hank's death. He had months in the cabin to reflect with no hint of remorse or a need for redemption.
Maybe so, but up until recently the ONLY person who Walt truly cared for was Jesse. If Walt realizes who he has become, and the terrible things he has done, he may have a moment and realize how he has been toward Jesse.
How is Walt fundamentally decent?
Almost every problem Walt has comes as result of his loyalty to his Jesse or Hank. All of his problems with Fring were a result of being loyal to Jesse (despite Jesse being an imbecile). The whole reason Jesse was in the mix with Fring in the first place was Walt trying to save Hank (after he beat up Jesse). He is loyal to Hank at the end (even after Hank makes very effort to destroy him) and loses most of his money because of it. Personally I could not believe he stood up for Hank at that point after Hank had tried to burn him down to feed his own ambitions. Walt would not have considered destroying Hank for his ambitions...... but Hank did not hesitate to try and destroy Walt for his.
Walt is fundamentally a loyal and honorable man who is surrounded by weak and disloyal people. His loyalty to those people destroys him. This is not much of stretch since Walt is written as the hero of the show...... so it seems likely I am not the only one to see it that way.