I don't know the details of the end or who kills who, but its important to remember what the show is about.
Walt's evil is a sickness and it infects people around him. His evil is contagious, ruthless, unending, uncurable, and only gets worse over time. Every gets infected. Everyone. The greed, anger, and bitterness that led to Walt starting to be a meth dealer has only gotten worse. Skylar has become lustful, greedy, and vengeful too. Even his adversaries Hank and Marie are now infected. Do you remember how little Hank cared if Jesse walked into a trap? He just wants revenge too. I can't see a scenario where everyone doesn't die or end up poor, alone, in jail, or crazy. His lung cancer is nothing compared to the cancer* of his evil, selfish, heart.
*hur hur hur CF3 said cancer. OMG WHAT A CANCER LOVER! Hey guys! Come make fun of CF3 for loving cancer!