All fair points. But I see no merit in spending good money on hardware just to run at 60fps. I normally do read threads very carefully, I think I can be forgiven for missing a couple of things here as I'm currently feeling pretty terrible with a bout of Covid. But that said, if he has 16GB already then that's also spunking unnecessary money as like you say, it does nothing for games. I like to have a couple of VMs running in the background, otherwise I'd have just gone for 16GB. Unless the OP also wants to do such things, I think we both agree that he's wasting his money here.
The examples you give about the 2060 are, as you say in the case of VR, niche examples, as is running AAA games at full details. Nobody can do that without the very best. But for the cost of a 2060 against a 3080, the 3080 is not worth that price difference for the improvement in performance you'd get at 1080p and with an older CPU. 1440p, different story.
As regards the 4790k, I agree it's a great chip and still relevant. I know this having had one and only have a 3700x because last year, I feared I might be out of work this year so upgraded while I could. Is the 3700x better? Yes, but only for my use case running VMs in the background, it can do far more simultaneous things than the 4790k. Is its gaming performance better than the i7? Yes, and certainly noticeable. But would I be able to go back to the i7's gaming performance? Absolutely, it still had 8 threads and performed admirably for such an old CPU. Thing is, spending big on a graphics card at this particular point in time could possibly mean not being able to upgrade system for a couple of years. And while the i7 is still relevant now, a lot can change in a year like it did with the 4-thread i5s. They started to struggle with games and within a year, most AAA games were maxing them out. So while the 4790k is good now, the longer time goes on, the more the chance it'll become less effective as a gaming chip.
Asking if your system can 'handle' a 3080 is pretty much letting people know you're considering buying one, I know he's a grown adult but buyer's remorse doesn't discriminate with age. I do get your point though, its their money to do with as they please.
You're right about 3080 availability, that's dire and will be so for some time. I guess from my point of view, this is also all academic if discussing 1080p gaming. I just don't think it's worth it as the emphasis then is on CPU, which is what we're discussing here. I ran the 4790k with the 2080 at 1440p, that's more balanced as you become more GPU limited and that's why the i7 could hold its own. But not 1080p, pairing a 3080 with a 7 year old chip for 1080p seems a bit futile to me.
All my opinion of course, which is what the forums are for. That's what I'd do, you may do different and the OP may again do different.