kzmich

If you plan to get 1440p monitor you should get as it was said above atleast 1070 but the price difference between 1070 and the ti version is minimal so I would proly recommend the 1070ti (when oced you can get performance of 1080). But everything depends on your budget. 1060 is suitable for 1080p60hz so would not go that way.

The 1060 6GB or RX 580 8GB are enought for UW 1080p and can max most games except poorly optimised ones

You're looking at GTX 1070 or above performance level for your requirements (PUBG has poor optimization, WOLCEN uses Cryengine, the same thing that gave Crysis its reputation), but at this point with new cards coming late this year, only the used 980ti makes sense because 10 series cards are still relatively expensive (not as crazy as it was, but still).
 
I'd rather call that resolution 1080p ultrawide. 2K itself refers to 1920 x 1080 while 2.5k refers to 2560 x 1440, neither match your actual specs.