"only 12 gb vram" oof I feel old

for what exactly do you need more than 12 gb ram?

I generally buy gpus to keep them for 5 to 6 years, so running out of vram will just suck

12gb of vram is more than enough for 4k, keep in mind that most games consume only 12-25% more vram going from 1080p to 4k as at 1080p they are already running downscaled 4k textures.

I was playing games at 5K (which is 78% more pixels than 4K) for a long time on 11GB cards, so 4K will be fine, at least for a while. I doubt devs will want to push even past 10GB usage, not to piss off 3080 buyers. As a side note what do you mean by "guess i will have to buy a 3090"? You're considering a 3070 in the other post, so a 3090 is obviously out of your budget, no? Why even think about an overkill card like that then...