4k to 2k? No way.

I've been recently looking at ultra wides and there are two that have stuck out. The asus pg348q and the Acer x34. That's if you want ultra wide otherwise I'd go with the asus mentioned above

For me, 2K is the sweatspot atm. I have a LG 32GK850-B. It is a VA Panel. Once i owned an ASUS PG279Q but the IPS-Glow was terrible. And i dont wanted a TN-Panel. I will switch to 4K someday. If 4K / HDR / GSYNC / 144Hz is affordable and it is an OLED or QLED (so maybe in 2030^^). For me the LG is the best compromise between all. But it is no Ultrawide.

I can only suggest you to order a 2K one, try it and if you are pleased, keep it or send it back. I dont want to miss GSYNC and 144Hz. 

And you can still supersample. Many games have that already in their options or you can do it via the nvidia control panel. It is not the same as 4K, i know that, but if you go the 2K-Way their are a few options for you. The personal taste matters the most, like with everything :)

Been running with 3 27" 2560 x 1440 screens for 2 years now and I have not been able to surround game properly till what I believe is NOW.
 
2 Hydrocopper's should get the job done properly!
 
That being said THIS gen I would recommend surround gaming or 4k on the biggest 1ms screen you can get your hands on.

Utrawide 3440 x 1440 is better than 4k60 imo, i've tried both. In that case you can get a nice Alienware 3440 x 1440 gsync 120hz for 999. I'd go with that.

This is a topic that I'm still torn on myself. I currently game on a high end 48" 4k samsung, but want to downsize slightly and pick up gsync. Also after having picked up an LG OLED tv, I don't want to ever buy a panel that isn't OLED again... it is such a night and day difference. I also hate that most of the best features are put into 27" displays (too small now imo), and the ultrawide format is not anything I'm interested in being non-standard from a cinema perspective. 

ComboSlicer
 
Last but not least 160fps vs 90 fps is night and day.

I just love the sound of that. 

Just because 2080ti will probably play all the titles of 2019 at 4k with at least 100fps, it doesn't mean a 4k monitor is the best solution.
Just like other members said above me, the ultra wide monitors at 1440p are also very nice.
The PLUS and MINUS points of ultra wide 1440p monitors in comparison with 4k are,
+ Higher frame rates
+ More future proof in case very demanding games come out
+ Generally ultra wide is making a big difference in immersion and also gives a tactical advantage in some games.
- Lower PPI
 
Personally I'm kinda happy with my 1080p monitor, so I can trade a big PPI boost for a slight PPI boost and all the other "plus" points of an ultra wide monitor.
Oh... and it has to be HDR !!

If you want to go Ultrawide I'd definitely do a 34" 3440x1440. Hell no to downgrading to 2K unless you want to go high refresh.

Also with a 2080ti, as seems the new most powerful card in the world under 2000$, with ray tracing enabled will not reach more than 25/30 fps in 4k. Its not acceptable. This is the current problem right now. It is an epochal change that had to be done at a high cost. I am playing in 4k since the new gtx 2080 making me do 40/55 fps. But also if you buy the new 4k monitor at 144 (actually 2500$), 2080ti isn’t be able to use ray tracing up 30fps. I have preorder an evga 2080ti but we will have to wait another 2/3 years and next 3080ti to be able to see ray tracing in full 4k on 144h monitor. by then we will pay those monitors the right price.