They're taking Walt by force, and after Jessie kills Todd, which he will do, they need Walt to cook permanantly.'
Leaving Hank and Gomez alive does nothing for them people.....
And Hank is not dying in the third to last episode, so unless you think the shootout continues for two more eps, he's going to live.
And I doubt, very highly, that we see Walt and Jesse cook ever again. Neither of them want to cook, neither of them need to cook.
His theory is fairly reasonable. Not likely in terms of real life or anything, yes, guys with machine guns tend not to let guys live, but these guys are obviously different in terms of how they do business, maybe Walt makes them let Hank and Gomie go.
Rest assured, Hank is in the final episode, and not in a flashback scene or something like that.