The best we can go off of is what system requirements looked like over the years. But keep in mind, these don't necessarily mean that the game will consume up to that much, but you should probably have that much if you want to run other things you'd normally do.
- 16GB recommended started showing up around 2021, but it wasn't starting to be required until 2023
- 12GB recommended started showing up around 2019, but it wasn't starting to be required until 2021
- 8GB recommended started showing up around 2013, but it wasn't starting to be required until 2015
- 4GB recommended started showing up around 2011, but it wasn't starting to be required until 2013
This is just poking around with games that were considered AAA quality of the time. But as you can see, while the jump from 4 to 8GB being required was kinda short, the jump from 8GB to 16GB required took a lot longer. Just out of curiosity, I wanted to see if there are any games that recommend more than 16GB of RAM, and so far Forspoken is one of them that recommends 24GB. Judging by
this video I found, the game seems to use up to 12GB of RAM, and in that person's computer, up to 19.5GB total was used.
There were articles floating around that Returnal recommends 32GB, but the official requirements from
Sony's site says 16GB unless you want the 4K configuration... which doesn't make sense to me other than Sony's expecting a lot of VRAM swapping. (
EDIT: I found a few videos showing Returnal and real time RAM usage and the game hovered around 12-14GB of RAM usage, assuming the value in the overlay they had was just for the game).
Ultimately though, this is kind of a moot point. Get what makes sense to you
now and worry about the future if it actually happens. I've seen a lot of testimonials of people who bought an HEDT platform (e.g., Threadripper) because they thought they would use the extra CPU horsepower in the future. That never actually happened.