Looking to upgrade – Just what to replace?

I've been looking to upgrade to something like 64gb of RAM however I'm still using DDR4. So future-proofing to a new motherboard and CPU with DDR5 sounds like a logical plan. However I'm not even sure if that would be worth it. I figure you guys would have a better idea of what I should look at upgrading.

CPU: Intel i7-8700k

Motherboard: ASRock Z390

RAM: 16gb DDR4 3200mhz

GPU: RX 6700XT

Let me know if I'm missing any specs, it's been years since I last looked at my hardware.