Nothing out in the market right now (under a 4090) is going to make for a great 4k card long-term if you like your games pretty (with higher-end settings and RT) and with what I would consider a decent FR.
5080 is not a 4k card (long-term), look at Assassin's Creed (mins with or w/o RT at 4k, including up-scaling to 4k), or many others.
It's mins are under the VRR range (48hz), and it will not get better with age. 1440pRT very similar story. It's going to be close now, and get worse (as specs increase for 1080p->4k up-scaling on next-gen consoles).
Those next-gen consoles will likely be just *slightly* faster than a 5080 with a lot more ram. nVIDIA is doing that on purpose, bc they know people don't know that (yet), or what that means.
The point of the matter is that it really doesn't make a lot of sense to go above 1440p rn, and this from a guy that uses a 4k OLED to game (at mostly 1440p->4k up-scaling, sometimes 1080p->4k).
The card that will give you that experience (1440p native raster and 'quality' upscaling RT) is a 9070 xt. Above that literally isn't going to be great long-term for high-end games. As I've said before, it's a racket.
Nobody wants to sell that card (yet), meaning 1440pRT->4k upscaling and keeping 60fps (or even long-term 48fps) because they know people won't upgrade for a long, long time.
So, personally, I wait. You do you but I don't think you'll be happy going this route. I would buy a 9070 xt and a decent 1440p monitor.
IMHO 6080 will be the card you (and I, or the Radeon alternative) want. It's not about 50% more performance (although it will be certainly that), it's about the thing you and I both want. Decent 4k.
FWIW, I think it will be 12288sp @ ~3700-3780/36000 256-bit (24 or 32GB). 5080 is 10752 @ 2640mhz/30000 (but only needs 22gbps ram) and 16GB.
Even if you OC a 5080, 6080 will likely be the difference between one being 1080p60 and the other 1440p60 at some point not super long from now, and the later ok to up-scale to 4k, the former not from 1080p.
As I've argued and will continue arguing, 5080 is a 1080pRT card that can up-scale to 4k kind-of, but you'll still likely need FG with high settings. I think for $1000 (actually way more than that usually) it's absurd.
The fact they've tricked people into believing it's better than that is amazing. People are about to get incredibly burned when the next-gen launches and that depreciates by a good half it's MSRP.
Because the markets are 1080pRT, 1440pRT, and 4kRT. The 9070 xt the first, 4090 the second, and not even a 5090 the last, yet next-gen they will have to fit into each of the current market tiers.
So think about that when 5080 isn't even a 1440pRT card, and will likely get replaced by a 70-class card that is, and a 80-class that can up-scale to 4k and still keep good performance (and a 90 that can do 4k native).
Personally, I would grab a 9070 xt (once the price settles) and a 120+ IPS 1440p monitor. If you feel compelled to upgrade (to 4k) when Rubin/UDNA launch, do that. I'm sure there will be good options then.
I would not be surprised if the prices you will pay for what I am suggesting are the difference in cost of attempting to do it now (with a 4k monitor + 5080) versus doing it then.
Monitors will get better (and cheaper), and the cards that do what you want will be available (and likely hundreds of dollars cheaper than most 5080's right now), as there will competition for that market.
A lot of competition; because many of us want that. You, me, and probably a ton other people on this forum and elsewhere.
Right now, there just isn't good 4k options. Anyone that tells you otherwise truly does not understand the RT situation.
They will keep complaining about games, even more-so after next-gen consoles, but the reality is that's where we're headed and nothing is a great option for longevity, esp for the price, outside a 9070 xt.