I honestly think that they should just stick with the PPK at this point because it's just so iconic, so synonymous with James Bond at this point.
If not, then I say give Bond some makebelieve updated PPK made by Q chambered in some sort of Gyrojet-esq Rocket Cartridge. Keep the exact same look as the PPK, just dress it up a bit to make it look more spytech/futuristic.
You know, for all the folks who apparently can't suspend their disbelief that a Spy with access to all sorts of Sci-Fi gadgets would carry an older style of firearm chambered in a less powerful cartridge.
The moment they begin to "update" Bond for the modern era is the moment that the series will inevitably go into a downward spiral as the character is gutted to fit modern sensibilities. I dunno about you, but I don't want to see a "modernized" James Bond equipped with a seldom used SIG P365, a man bun, stretch pants, and a Manscape bodyhair trimmer thats actually a stun gun on his quest to rid the world of Social Injustice. *shudders*