AMD will be announcing Ryzen 3rd Gen at GDC (Mid-March)., meaning we'll be looking at a May - July, Launch Window.
May will in-fact be the 50th Anniversary for AMD... so we can expect at the very least a very similar Anniversary Product, like Intel had last year with the i9 8086K to celebrate the 50th Anniversary of the 8086 (x86) Processor.
Ryzen 3rd Gen will be AM4 Compatible, so provided the Motherboard BIOS is up-to-date it will work on any AM4 Motherboard (300/400/500-Series Chipset)., although new Features / Functionality will likely only be supported on the 500-Series Chipset.
As a note the 500-Series (unlike the previous 2 Chipsets) is thankfully being produced In-House again., so we can expect them to be back up to the Quality of their previous Chipsets.
So, I'd personally recommend a 500-Series Board if you can get one... it also likely means the A520, B550 and X570 should all be available at the same time rather than staggered.
Beyond this., it's likely that we'll also be getting the announcement of Navi at GDC as well.
With them launching it in June-July either at or shortly following Computex. I've never been a big fan of their Computex Launches, as said Keynote is always so heavily focused on OEM Laptops; because well said Laptop Cycle tends to being in Sept-Nov in preparation for the Holiday Period.
