I'm not sure either, The fact that these cost a fair bit more than the Intel equivalents has me stalling, Plus I want a high end X370 MATX if possible. I get why Asus etc had added the extra on, Presumably because AMD are saying the platforms good until 2020 so unlike Intel we aren't being forced onto a new board practically every generation. I haven't even ordered a cpu yet, I figured on waiting until afterVega but I've bought some 3000mhz DDR4 as that's going to be needed regardless of the motherboard, cpu or brand.
I'm just waiting till the 2nd to make my mind up on whether to go Ryzen or not. I'm pretty sure I will be I want to see what Anandtech says about it because I trust their reviews. I think I might go for the Asus seeing as I have an Asus motherboard at the moment and they seem to support their motherboards pretty well for quite a long time.