For what it's worth, I bought a package of XTOL from Adorama 3 weeks ago and mixed it up into stock solution, and it's been fine. I threw away the packaging, but I'm 99% sure it's the 'new' stuff. Adorama's product description said it was, and Adorama was out-of-stock on XTOL for 2-3+ months while the manufacturing changeover was happening, so it seems impossible that I could have somehow ended up with a package of the old stuff.
I've developed 6 or 7 rolls of 120 film in it over the past 3 weeks — Tri-X, TMAX 400, and HP5+ — at a 1+1 dilution and all developed normally, i.e. as I expected based on using XTOL for a couple of years. Again, I don't have the packaging anymore, so I don't know if it was the same batch that's noted in Kodak's tweet. I still have about 3 liters of stock solution left; as of a week ago it was working at full strength.
Also FWIW, during the period that XTOL was unavailable, I bought a package of the Eco Pro LegacyPro Ascorbic Acid developer and used it with 3-4 rolls of film over about a month. It worked just fine, and exactly like XTOL as far as I can tell (I didn't do any meticulous tests of it; just developed some film and got the results I expected.)