Some good news for fans like me collecting the Annual Japanese Transformers Generations book, who thought that the Beast Wars Generations-styled book in December was the end of the series... the publisher Hero X has just announced by twitter that there will be a 2021 book, expected out during our Autumn (somewhere from March to May).
My guess is that this is just a one-off delay for this volume, as the pandemic would have delayed a lot of projects, particularly ones like this that would require a lot of interactive work with TakaraTomy to photograph all of the toys from their vault.

Since they use the year on the cover that is the year after the toys that are being featured, this one should include mostly 2020 toys, along with some early 2021 toys (with the books being out in December, those early "next year" toys are often a pre-release look... but this time, if they are early 2021 toys, they will probably all be out by the time this volume is released).