The game content is also a big part. How optimized is it, does it have lots of high quality textures and demanding special effects like volumetrics. Games like Beat Saber might just work fine using a 1080Ti. If not you could reduce supersampling to 0.8 for example. Business apps should be fine too and the 8K-X should shine at that.
Then as you say we have the new series in July with the 1180 being almost 50%? faster than the 1080 so we could assume the 1180Ti will be near 50% faster than the 1080Ti. That's a serious punch.
As that video shows, If NVidia add hardware acceleration for real-time ray tracing then that could be even more optimal than current game engine code to produce things like reflections, shadows, global illumination, path tracing, volumes, fluids and all the other benefits that would come from it as hardware can always calculate faster than the equivalent software emulation.
On a side note, major 3D visualisation packages will have some of their profits sucked away by this as game studios could save tens of thousands of dollars a year on subscription services (e.g. one seat of 3DSMax is £1,740 per year) by doing all their cut scenes / texture baking etc right inside the game engine like Unity or Unreal instead.
By the time the 2080Ti releases, Pimax would have worked out its eye tracking module and hopefully developers will start to issue updates to their games that compiles in the engine's foveated rendering features. that's a huge saving in GPU demand. so no need to spend $$$ on the best GPUs available.
In addition to that VR-SLI/Crossfire should appear on the map again as the demand for it would increase. Single GPU power will never keep up with display panel advancements.