For 1080p, I would never.  You are already way exceeding what you "need" for 1080p, in my opinion.
 
For reference, I am using a GTX 1080 with a 4k monitor.
 
I'm nuts, but so are you in the other direction.

The only reason to run that high-end of a GPU on a 1080p monitor is e-sports. At 1080p, I'd be looking at 3080's, 3070, 3070ti, 4070, etc., but I understand your main thought process is to have it last you 6 years, which makes you want to aim higher. I think that makes sense...if you're planning to upgrade your CPU in a couple years. Most games will be CPU-bottlenecked with what you have if you drop in a 4080. Will that be true 3 years from now if you drop in whatever high-end CPU is out then? Maybe not...so you'd be buying a GPU more powerful than you can actually put to use for a couple years knowing you'll drive it harder in the future. I don't think most people shop that way, but I have done that before, so i certainly can't knock you for it.
 
I guess the one possible caveat there is if you're really really wanting to get some higher FPS in a new unoptimized UE5 game that has ray tracing you can't turn off (like Ark: Survival Ascended) as some of those need a 13900k+ and 4090 to get 60FPS at 1080p with all the settings maxed out. If those games are what we can expect over the next 6 years, I guess you'd be laughing when you upgrade your CPU and already have a 4080.

Frankly, I run the Asus TUF 4070TI OC for two reasons.  When I built my system, the 4080 and 4090 wouldn't fit...but this particular model did.  However, I have to admit that I am impressed by this model.  Even though it only has 12 GB of VRAM, it works great with my G Sync monitor at 170 HZ (1440p).  I have never come across any issues with running out of VRAM while gaming.  In most benchmarks...it holds up to the 3090 about 98 percent of the time and 3090 TI about 70 percent of the time.  It has plenty of horsepower and is really solid. 
 
You can wait for the super series to release...and the 4070 TI Super is supposed to have 16 GB VRAM vs the 12 with more cores.  Expect to pay about $900 to $1000 for it.   OR...see if you can get a 4070 TI 12 GB, cheaper with the release of the new one.  Either way...you can't go wrong.

Great hardware