I would just wait until you get the CPU if you're going to be on another platform entirely right now. If a new chipset comes alongside Zen 3, you have more options available by waiting, and if it doesn't, X570 isn't going anywhere anyway. If anything, there's a bit of an availability and pricing issue with it right now (and even B550 boards), or at least there was when I was buying a few weeks back. Even if that has totally resolved itself though, you'd probably be gaining nothing to buy it now. You likely only have more options and availability if you wait.
Now if you were planning to buy a Ryzen 3000 series in the interim and upgrade later, that's another matter. But with Zen 3 months and months (at least) away, I don't see the point in buying a motherboard yet.
"The heart has it's reasons that reason knows nothing of."