Next iteration of AMD chipsets?

[Kabrevre]

   Hi guys, I made some compromises in my system so I could by it sooner and chose to go with a B450 board. (MSI B450-A pro)
The quick and dirty fact is that I'm just not happy with it, and now that I have some money to spend on an X570 board, I'm wondering if I should wait considering the B550 range launched recently. Is there anything that the X570 will be moving up to? If not then I'm in the clear, I just don't want another situation where I buy - install - get everything set up - then a better choice comes out. I care a bit less about compatibility, and a bit more about long term usability once I pick a strong set of core components. I bought a Phenom II 1090T soon after release and I got ten years out of that, and I'd like to get another ten years from my next big move up. I'm looking at the Ryzen 9 3900x as a good choice, but I hear whispers that I should wait to see what comes after the R9 options. I'm not at all impressed by the XT CPU range, but I'm worried that the XTs might be the last AM4 CPUs we get for a while.

Thanks very much for your help.

[Enderman]

The 4000 series and X670 coming in the next few months are the last CPUs for AM4.