Pretty sure that Asus will release an ITX board for AM4 and Zen. I remember reading an article stating they do cooperate closely with AMD, and will release boards for AM4 when Zen arrives.
Impact VII was better than the VIII in my opinion. It had M.2 SSD, and an overall nicer color theme, even if I am also tired of red & black. Pretty sure that a M.2 SSD slot will return on the next Impact, or the itx board for AM4. It was simply a mistake from Asus to not include it. If they want, they can probably replace the SATA Express port with a U.2 port, and we get both M.2 and U.2. The problem is that these small M.2 SSDs easily throttle, they are in need of heatsinks.
Regarding color variety in the ITX market, it sucks. All the love goes to ATX still. A few years back Asus did release some more varieties of ITX boards. I remember a yellow one, and a blue one. Today we only get some reddish ones with abysmal gamer logos you just want to rip off. I hope they will give itx boards some more love the next generation. How about a pure black one? Or a Sabertooth themed one? Or a remake of that blue one a few years back? Really don't understand why we can't get more professional looking ones, that also have all the features.