"Three shall be Peverell's sons and three their devices by which Death shall be defeated."

When I first saw this line, I didn't think it was very important, but could it mean that Harry is actually going to use the three Deathly Hallows to defeat death, i.e. make everyone immortal?

I confess, I hadn't paid that much attention to the possibility, because the canonical Deathly Hallows don't seem well-suited for the purpose. But I suppose there could be some effect where when the Elder Wand is used to cast the Patronus 2.0, you get an Uber Patronus, or maybe it lets you lets you kill a hundred Dementors without depleting your own life force, or something. And I suppose the Resurrection Stone could easily get an upgrade from canon. But how could the Invisibility Cloak be used as part of the process of granting immortality, beyond hiding from Dementors? Could hiding from Dementors become really important at the climax somehow? Doesn't seem like it, if the Elder Wand + Patronus 2.0 takes care of the Dementors, hmmm...