"The select beta BIOSes will enable a one-way upgrade path for AMD Ryzen Processors with “Zen 3,” coming later this year. Flashing back to an older BIOS version will not be supported. " - if the beta BIOS doesn't work you can't go back :-(
"Will not be supported" does not necessarily mean the same thing as "cannot go back". The wording is kind of vague, and may simply mean that they will not provide official support for it if things go wrong. Perhaps that will be up to motherboard manufacturers. If I had to guess, at the very least I would expect boards supporting CPU-less BIOS flashing, like many of MSI's B450 models, might allow for it.
Just do the smart thing and buy x570--or B550. Skip all of the hassle this will entail.
This is more for people upgrading existing systems. Once B550 launches, there probably won't be much point in going with a B450 or X470 motherboard for a new system with a 3000-series or newer processor. And if one has one of those boards in their system already, there would arguably be more hassle and cost involved with replacing that than simply upgrading a BIOS and dropping in the new CPU.
There may be a Zen 3+ in 2021 since Zen 4 is only slated for 2022.
It's possible, though it could just be that Zen4 may be coming in early 2022. Each generation of Ryzen has lasted more than a year so far, with the 3000-series launching almost 15 months after the 2000 series. If the 4000-series comes around 15 months later, and the 5000-series another 15 months after that, then that could be right around January of 2022.
Of course, it's possible that DDR5 still won't be available at consumer-friendly prices at that point. If they don't wait quite that long between generations, they could sneak another generation in, and save the launch of new motherboards running DDR5 until near the end of 2022.
And yet again it seems that us users of X370 motherboards, those of us who had the audacity to support who was at the time a ridiculed near bankrupt company still putting out much slower chips than Intel (and will not regain the lead until Zen 3) and made to buy even more expensive RAM than their Intel counterparts due to very fickle compatibility get bent over the barrel and taken up the tailpipe...
Remind me again why I support AMD?
"Support through 2020" was advertised, yet we aren't getting support through 2020, that's a pretty clearcut wrong, no matter how much AMD tries to erase the past and change "through" to "until".
I'm pretty sure their official wording has always been "until" 2020. Even when AM4 first came out, there was some uncertainly as to whether that would include support for processors launching in 2020 or not. And even if they happened to say "through 2020" at some point, the current Ryzen 3000 processors are still supported on those boards and are still the current generation in 2020 as of this point.
As for "bending you over backwards", I would hardly say that's the case. You are now able to run Ryzen 3000 chips with relatively significant IPC gains and up to 16 cores on your first-gen board, and those higher core-counts are not something anyone was really expecting at Ryzen's launch. Even a Ryzen 3600 for well under $200 outperforms the 1800X by a decent margin at most tasks, and it often even exceeds its performance at heavily multithreaded tasks despite its core deficit. There are significant upgrade options available over first and second-gen parts, so you hardly got shafted.
The concern here was more for those who bought a 3000-series processor with a 400-series board within the last year, who may have been expecting to get at least one generational upgrade out of it. Since AMD didn't release a mid-range 500-series board for a year following the Ryzen 3000 launch, B450 has been the mid-range option for this generation. Had they launched B550 a year ago, this might have been less of a concern.