You're looking purely at nomenclature, which makes no sense for reasons that I mentioned earlier. When you focus on nomenclature, you get inconsistencies and ironies like high end Kepler GPUs such as the GTX 780 Ti and Kepler Titan being inferior to new "midrange" cards like the GTX 1060..
High end, midrange, low end are all relative terms. The only absolute metric is performance, and that is what ultimately determines the pricing of a GPU.
As such, the GTX 1080 provides the foundation of NVidia's high end performance bracket. The GTX 1070 is an entry level high end card, whilst the GTX 1080 is the high end card. The Titan XP and the upcoming GTX 1080 Ti are ultra high end cards..
NVidia has segmented its high end bracket for a long time now to exploit performance driven consumers that will pony up a lot more money for their GPUs than anyone else..
No, it's mid range. Take literally any measurable metric, let's take
CUDA cores for example.
GP100 (DGX-1) -> 3840 Cores
GP102 (Titan XP) -> 3584 Cores
GP104 (GTX 1080) -> 2560 Cores
GP106 (GTX 1060) -> 1280 Cores
GP107 (GTX 1050 Ti) -> 768 Cores
Wow, yet again, there are 2 dies with more cores and 2 dies with less cores. Middle. If you look at the change in cores when you switch cards, you can choose to go up and gain 50% cores or you can choose to go down and lose 50% cores. That is literally the definition of middle. If you go down again (1060 -> 1050 ti) you lose 40% relative to the 1060 (another 20% relative to the 1080). Which would make 1080 upper-midrange since still 2 more higher SKUs exist above it.
Let's take
RAM capacity as another measurement
GP100 (DGX-1) -> 16GB HBM2 RAM
GP102 (Titan XP) -> 12GB GDDR5X
GP104 (GTX 1080) ->8GB GDDR5X
GP106 (GTX 1060) -> 6GB GDDR5X
GP107 (GTX 1050 Ti) -> 4GB GDDR5X
Literally smack in the middle, again. You can even talk memory tech as midrange. 3 techs from a purely bandwidth and capacity standpoint, HBM = fastest, gddr5x = second fastest, gddr5 = third fastest. The middle memory tech.
Memory bandwidth
GP100 (DGX-1) -> 720 GB/s
GP102 (Titan XP) -> 480 GB/s
GP104 (GTX 1080) -> 320 GB/s
GP106 (GTX 1060) -> 192 GB/s
GP107 (GTX 1050 Ti) -> 112 GB/s
Middle. Again.
It's the midrange card, like every x04 card before it. This is beyond nomenclature. The specs are in the middle.
Try it yourself with die size, TFLOPS compute, etc. and see what happens.