A proposal for how Harry could WIN (defeat death). Tl:DR at end.

There has been a TON of reference to harry's goal to defeat Death. Hermione's death has merely sped up the timetable and increased Harry's chance of success...though it has also increased the chance of complete, utter, catastrophy if he fails.

It is most likely that Harry will use three magical items to do it, which need not be the deathly hallows. ("...three items needed to complete the cycle of infinite wishes/infinite wish cycle".

1. "He is here! the one who will tear apart the very stars of heaven" -so harry WILL destroy the stars with...~99% certainty, though that doesn't mean anyone needs to remember it happening "the next day".
2. "...potion cannot be hotter than the goblins fire[that made the knut, even though the knut is now quite cold]" -so for more power, find a hotter furnace that was used to make something. 3-Harry now knows about cursed fire, which uses only ONE DROP of blood to pay an estimated 70-98% of the manna cost. He also has the sheer drive to control it, though he really does need to pass a lesser trial first as a safety-precaution -Rational!harry has already shown himself to be mildly competent when it comes to potion-making....wait, no, that's not quite right: he has shown himself to be capable of EDITING the ingredients of a potion.

so. Let's make The Big Potion of Life. step 1. obtain cauldron. the actual size is not particularly relevant. step 2.: put [universe-solar system] [or even entire universe, but that's annoyingly risky] into cauldron with a space-folding spell. step 3: heat cauldron contents with massive cursed-fire spell (note: rob some blood banks) step 4: Add the resurrection stone or philospher's stone and some pheonix tears.
step 5: Stir with the elder wand while wearing The Cloak.

WARNING: DO NOT ATTEMPT ON THURSDAY. DO NOT ADD TIME-TURNER DUST WITHOUT FIRST UNDERSTANDING TIME! DO NOT LET DRACO MALFOY TOSS A GLASS JAR INTO THE CAULDRON! and for armok's sake, DO NOT ATTEMPT IN SNAPE'S CLASSROOM! that is all.

Tl:dR: make a potion powered by THE BIG BANG and guide it with the deathly hallows.