I am able to maintain 60 on low, 40-50 on ultra at 3440x1440 but my pc is far from average. I would say the final release will be much much much more optimized for midrange- higher end pcs.
I have found the expected performance on these graphics⊠it is not official, it is only calculated to act like that, but either way you can imagine a little how it would work. Developers also said this week, game has been optimized on their computers to have smooth 60 FPS. So I guess whoever is using GTX 1080 will get 60 FPS on highest details.
http://kingdomcome.czech-games.net/2016/11/24/optimalizace-hry-znacne-pokrocila/