Is it really so hard to understand? Firstly X wouldn’t be pronounced 10, and it is the internal name right now. iPhone 10 (if they stick with the numbers) would be called ‘iPhone 10’ . But the most likely in my mind right now is Edition.iPhone Edition and iPhone X(10??) make sense but iPhone 8 doesnt make any sense?
I wouldn't mind them calling it iPhone Pro it fits the line of other devices (iPad Pro, MacBook Pro, iMac Pro and so on) but I do think the pro features will be more like:If it has a 120hz Promotion display like the new iPad Pros then I'm on Board.
However. I think very possibly Apple will be getting rid of Numbered Names altogether. Because they are behind Samsung now. Galaxy 8s Plus vs the IPhone 7s Plus
IMO total speculation the 7s line will be renamed IPhone Edition for both sizes confusing but you own a MacBook Pro regardless of size you don't own a MacBook Pro Plus.
And the OLED 5.8" rumored iPhone 8 will IMO be called the IPhone Pro
#1. OLED Display 125%sRGB Color Gamut coverage
#3. Pro Phtography with a mega new camera new Specs.
#4. The A11 will be Feature HMP heterogeneous multi processing
#5. 4GB RAM
Just enough features to make it "Pro" then next years 6.3" OLED IPhone Pro will feature the 120hz Promotion display. And last years 5.8" Pro with new Specs but no 120hz display will just be called IPhone Edition.