OK, FINALLY managed to find a 3700x in stock at Newegg (still no dice at Amazon) and have one on the way. Since, that happened I went to look to see if x370 would be at a serious performance deficit versus x570 and whether people with my MB (Taichi x370) were having problems with these CPUs. The good news is no and no.
https://www.overclock3d.net/reviews/cpu_mainboard/amd_x370_vs_x470_vs_x570_-_3600x_3700x_review/1
In case anyone else is in a situation with having a robust x370 or even x470 MB and is thinking about whether or not to pair it with the new CPUs. There is virtually no performance difference in the vast majority of cases.
So as long as you don't need the new features (PCIE 4.0 being the biggest one), there's not really a need to get a new MB.
In my case, everything up to a 3900x will work in my MB, and people have had success running RAM at 3600+ speeds. However, some people have needed to tweak settings to get it to not run at max power all the time. Hopefully, my adventure will be one of the more trouble free ones.
While I want to jump on PCIE 4.0, I also don't want to have active cooling with those tiny fans on my MB chipset. It's an area of potential failure that I don't want to deal with, and all x570 boards I looked at have active cooling for the chipset.
Anyway, Kudos to AMD and their partners for supporting the new CPUs all the way back to the x370 boards. It's very nice to have the option to keep using my existing MB...and without a significant performance deficit.
Regards,
SB