I have read many theories about how Breaking Bad ends, very good ones out there. None of them match mine so here it is:
Currently there’s only 7 episodes left. So the first episode of the second half of Season 5 just aired this past Sunday. There’s a flash-forward scene showing Walter going back to his home, which is messed up most-likely raided by DEA or someone else. Walt goes back home to get the ricin he has been hiding for a while.
So all we know now is that people in town know that Walt is Heisenberg. Since its tagged in the house and Walt’s neighbor trips out when she sees him again. This is approximately a few months after his confrontation with Hank. We do not know who is alive and dead at this point.
Vince Gilligan has claimed that the plot will be resolved by looping back to events and characters from previous seasons, and bringing everything full-circle. Everything started in episode one when Walt gets diagnosed with cancer. According to Walt, the cancer has comeback in Season 5. So this might be a lame ending but I think Walt will die of cancer (or ricin poisoning). What happens in between or what he decides to do before he goes out is what is interesting though.
We also find out Walt is using a different identity and living in New Hampshire (first scene of EP9 S5). My guess is Walt uses Saul’s guy that gives you a new identity and goes into hiding (with his family). He came back though, bought an M60 and got his ricin back, probably to get revenge?
My theory is that Lydia finds out about Hank and sees him as a threat to her operation. Walt is out of the meth business but Lydia needs him back. At this point Hank has decided to keep quiet about Walt, since he will die soon of cancer anyways. But Hank isn’t the only one that knows about Walt though, in the preview of Episode 10 we hear Hank telling someone (Marie perhaps?) about Heisenberg/Walt.
Lydia eventually kills Hank (and Marie?) to avoid him turning Walt to the DEA. This causes Marie(if alive or whoever also knows the secret) to tell everything to the cops and DEA. Then DEA busts into Walt’s house but at this point him and his family are in hiding.
When Walt said his cancer came back he also mentioned he only has 6 months to live. So when he comes back home, this is very near till his end. I think he gets the ricin to use it on himself just to hurry up the process after he causes damage with the M60.
Even though Walt is a monster according to Hank, he did saved him and payed for his recovery. So deep down Walt cares about his family even Hank and Marie. He comes back to town with the M60 to kill Lydia (for revenge) and destroy the Meth operation (quality of meth went down, hurts his ego, etc). Why is she in town? not sure but I think this is how it ends before Walt dies of ricin most likely.
The ricin is important because it keeps coming back and Breaking Bad is good at foreshadowing. If my theory is wrong then it’s gonna be used to deal with Hank/Lydia…?
Only thing left to discuss is Jesse. Sadly, I think Walt will kill him. Somehow Jesse will find out about Brock (probably about Jane too) and confront Walt but end up dead. This probably won’t happen in the next episode but very soon.
At the end, Walt’s kids and wife end alive and wealthy. Which is what Walter wanted when he decided to get into the Meth business.