>XBox and PS4 Pro are bad examples to use. Those systems have far weaker GPUs, and the textures aren't truly 4k.
Textures are the same as v.high/high on PC the only thing that some PC games add is an uncompressed texture pack which are simply stupid to begin with.
Xbox One X is a great example of a system that can push 4K or near 4K gaming because it does so pretty darn well.
The memory capacity is really not an issue with 8GB, in fact the only cases where the 2080 really pulls a head of the 1080ti is in higher resolutions especially 4K.
>if you enter a game with 4k texture packs (or 8k texture packs, like Star Citizen), you can expect your memory usage to spike significantly. 8GB is still sufficient, but gamers are expecting better and better textures.
Most textures in a game are well beyond 4 or even 8K regardless of the resolution, heck a simple texture atlas is huge.
Star Citizen is a crap game to use as an example as both the textures are overall simply horrid and it make PUBG looks like a well optimized title.
Overall the 2080 gives you RTX which is RT + Tensor Cores which will become very important as WinML/DirectML games begin to ship since NVIDIA both assisted Microsoft in defining the spec and it's essentially tailored for their Tensor Cores, you get concurrent Int/FP execution per ALU which will give NVIDIA a huge boost as integer shaders (e.g. compute shaders with heavy bool logic) will become more common and you get a more mature ecosystem, better encode/decode and various other small QoL improvements.
For gaming specifically the Radeon 7 doesn't have anything to offer other than to those that care more about the brand than what they get for their investment.
I really miss the days of the HD4000 series or the days when the R300, and sadly I don't see AMD getting out of this cycle any time soon, Fiji was late and underwhelming, Vega was late and underwhelming, and now Radeon 7 is late and underwhelming.
If Navi is another mid range GPU will see 15%-20% improevemnt over Polaris if we're lucky, once we get closer to Feb 7th I'm pretty sure we'll see that in 1080p there is likely no difference between VEGA64 and Radeon 7 and the only place we see the difference is in 4K due to slightly higher fill rate and more bandwidth since AMD still can't get delta compression to work correctly.