In the last episode, they don't actually show Walter White dying. They only show him lying on the floor.
Is it possible for them to continue the story from there?
According to the narrative of the program, it seems that Walter White is dead. However, if one looks at how he was wounded it is conceivable that he wouldn't have died from the wound that he received and that he simply became unconscious at the end of the episode.
While an M-60 fires a 7.62 (.30 cal) round, its bullets are copper jacket military rounds. These rounds don't expand and often inflict non-fatal wounds if they don't strike major organs or blood vessels. As demonstrated in the episode "Felina", the series denouement, Walter isn't struck directly by a rounds but is hit by a ricochet. This could cause a serious injury and perhaps an incapacitating one; however death seems to be a stretch.
Assuming that Walt's injury (on his lower right side) could have struck his liver or his renal artery and thus caused him to bleed out internally. Unfortunately, such a wound would have made it impossible for him to have walked out of the neo-Nazi's hideout and around for what would have been at least ten minutes. Given that the police shown to have arrived within seconds of Walt's collapse, he could have easily been saved if paramedics had been called.
The series states that Walter White is dead. The injury that he received could have been easily survivable.