Here's the real proof that Samsung will move from Galaxy A5 or A7 (2018), to A8 and A8+ naming
Samsung is heavily rumored to skip a step with its midrange Galaxy A line, going directly to an A8 and A8 Plus naming scheme, instead of sticking with A3, A5 or A7 (2018) model titles.
Releasing an A8 and A8 Plus models would move Samsung's midrangers in lockstep with the flagship Galaxy S line, simplifying its roster, and leaving users only two choices of size and pricing to pick from in the categories. There is further evidence for this shift, as you can see in the Bluetooth SIG regulatory filing below, for one "Galaxy A8" handset, revealed today. The model number is denoted as SM-A530F.
Given that the Galaxy A5 (2017) is SM-A520F, it would be logical to deduce that its successor will be called Galaxy A8, instead of A5(2018). Where does that leave the already-released Galaxy A8 from back in 2015/2016, remains to be heard, but we doubt these oldies will be an obstacle for Samsung to change its naming scheme in the midrange.
After all, if the company plans a move to the Infinity Display design for its more affordable portfolio, too, and fit an eventual A5 in the current A3 body, the A7 in an A5 one, and so on, this would negate the need for the smallest and weakest link in the A-line, so the move to the A8 and A8 Plus titles actually makes sense. Oh, we almost forgot, the new Samsung midrangers are apparently coming with the latest Bluetooth 5.0 standard, and there is even a "DS" or dual SIM version, as usual, neat.