I think Hank, Gomey, and Todd die in the shootout. That means Jack and crew need a cook. It's got to be either Jesse or Walt. We know Walt escapes somehow, because he's free in the flash forward. That means either he gets captured by Jack's crew after the shootout and is forced to cook for them, or Jesse does. My money is on Jesse being captured and forced to cook. Here's why.
In the flash forward Walt has just bought the M-60 machine gun. Vince has said this is because Walt is going back to save someone. OK, who?
Let's consider the possibilities. It's got to be family, or Jesse, Walt's surrogate son. If Hank is dead (and I think he is after the shootout), then Marie will freak out when she learns of his death. Marie will call Skyler and tell her, and that Walt was there and had something to do with it, and then Skyler will freak out, fearing for the safety of her children (and rightly so). This will prompt Marie, Skyler, Walt Jr., and Holly to flee the house. Most likely, they will run to the DEA for help in relocating via Witness Protection or something similar. They vacate their respective houses, and disappear to some far away place where Walt doesn't know where they are. They do not contact Walt again. To him, they have disappeared and he will not see them again before his cancer kills him. This means he has lost his family.
OK, that leaves Jesse as the one Walt is going to save. Save from whom? Jack and crew, of course.
Walt has to flee his house too, as now the DEA knows he's Heisenberg because Marie will have told them after Hank's and Gomez's deaths in the desert. Walt is now fleeing from the DEA and Jack's crew, because he knows they need a cook after Todd is killed and most likely they want him. He does not want to be their indentured servant, and Walt is not going to spend his final days on earth working for anyone.
So Jack and his crew kidnap Jesse and make him cook. Lydia remains involved so that she can distribute Jesse's crystal blue persuasion in the Czech Republic and make everyone big bucks. Jack and Lydia are likely to clash, and I predict Lydia will end up dead in the desert too.
This leaves the big showdown for Walt to return from hiding with his M-60, on a suicide mission (he's going to die soon anyway, and he no longer has his family) to save Jesse, the only person he has left that is close to him (and who is no longer a threat to his family). Why does he need the vial of ricin? To show to Jesse after he rescues him, lying to him again, that he still has the ricin and couldn't have poisoned Brock.
Will Walt be successful in rescuing Jesse? I have no idea, but I think the assault on Jack and company's meth manufacturing facility is going to be the final showdown. Walt will get mortally wounded and possibly die in Jesse's arms or something, or the cancer will get him shortly thereafter. Someone will find the money and retrieve it, or it will still be buried, unknown to anyone but Jesse, after Walt dies. Maybe Walt's dying wish to Jesse is that he retrieve the money and see that Walt's kids get it. Jesse might go for that, as he cares about kids. That would be a satisfying ending of sorts, but I'd rather see Walt die with all the money gone, his efforts at being a murderous drug kingpin all in vain.
If anyone ends up with the money, I'd love to see it be Huell. After he learns from the TV news that Hank and Gomez were killed in the desert, he's going to put two and two together and figure that since Walt returned the van with a shovel and the van covered in dirt, that means Walt must have buried the money in all those barrels out there where the DEA agents were killed. He can find it. No one else knows it's there but Walt and Jesse. As I mentioned earlier in the thread, I would love to have the final shot of the last episode be Huell lying on a beach in Mexico with pretty girls bringing him fancy drinks and fanning him. "Mexico. All's I'm sayin'."