Here's something to consider: every time people said "x ram is enough" they ended up with egg on their face. This gen. The gen before it. And on and on it goes. Sadly you can see if you go watch those arguments happen back then we see the same discussions today, almost to the letter, as if what's being said doesn't matter it just has to be repeated.
The simple facts are: vram usage is heavily dependent on the game, the resolution, the settings, and other features made available. There is no universal answer & we don't know how next-gen games will use vram & what settings they will/won't allow.
All I know is that at 4K there's several games which struggle with "just" 8 GB. Hell, there's situations where there's some issues even at 1440p. So looking at it like that, I wouldn't personally buy the 3080 10 GB if I didn't expect to sell it off before the next arch hits. It just makes no sense, texture quality costs almost nothing in terms of performance but has huge image quality implications, same for various image streaming options. Those are just not things I'd want to turn down, ever.
Something else to consider is this - as you add RT you further increase memory requirements which may tip you over what you would otherwise have under just rasterisation. So then you have to make further trade-offs. And don't expect DLSS to save your ass, because not every game will have it & there will still be major games that partner with AMD and therefore you can expect Nvidia features to not be there for them.
People who think RTX IO (Direct Storage) will help with this fundamentally misunderstand what that technology does, and as said above by iD's lead programmer (and even Nvidia themselves) - it's in no way a substitute for memory. It's simply too slow.
Likewise improved compression & increased memory bandwidth really end up doing the same thing - getting things faster into memory but you still need a certain amount per "scene" below which you cannot go and then compensate with with more bandwidth.
If someone wants to buy a GPU to last them the whole console-gen I'd very much recommend against buying a 10 GB card, especially as we know 16 GB & 20 GB cards are on the way as soon as October/November. If you just want a GPU for Cyberpunk & would upgrade again in 2 years then yeah - go for it.