dalauder :
There's just no loyalty from Intel and AMD seems to do everything they can to maintain compatibility.
Even if you have compatibility, using a new CPU on an old motherboard or vice-versa usually comes at the expense of forgoing some if not most of the new CPU or chipset's benefits and most people aren't going to do that. I know I'd have persistent nagging in the back of my head if I knew the CPU I put on a board is stunting the board's functionality in some significant way or vice-versa.
I expect Zen 2 to have a faster chipset link to support PCIe 3.0 on chipset lanes instead of 2.0 on current AM4 chipsets to close the IO gap with Intel's 170/270 chipsets. If that happens, you'll need a new motherboard and CPU to get many of the refreshed platform's benefits. Yes, it may be compatible, with an increasing number of caveats for each generation in-between.