I'm a 3d modeler and joined game freak January last year. I didnt get to work on Sword and Shield but I instead was put on the A team who had just started development on a second set of games called Definite Diamond and Fluxing Pearl which are sort of a "reimagination" of the games you might know as Diamond and Pearl, while the B team was finishing Sword and Shield. The B team has been working on the next games after Definite Diamond and Fluxing Pearl which are slated for 2022, since August/September 2019. A smaller team have been working on the DLCs for Sword and Shield and are planning the DLC for Definite Diamond and Fluxing Pearl which will come out in February 2022. (Unlike Sword and Shield, there is only 1 DLC for Definite Diamond and Fluxing Pearl and will have a shorter marketing campaign to make room for the 2022 games' announcement.)

I can't say much about the 2022 games since the different teams dont really cross communicate unless necessary (such as release dates, assets etc.) so I'll just tell you what I know about the games our team has been working on.

Definite Diamond and Fluxing Pearl take place in the Sinnoh region (you'll know this from Diamond and Pearl), and the visuals and sounds have been greatly updated and look and feel very similar to Sword and Shield. All the Pokemon that were made available in DLC 2 for Sword and Shield are available in Definite Diamond and Fluxing Pearl (I'll call them DD and FP from now), as well as a number of new Pokemon such as the three starter Pokemon from Diamond and Pearl, Geodude, Crabraler, Deerling etc. and an update for Sword and Shield will be released on the same day as DD and FP's release day to ensure compatibility. The DLC for DD and FP will bring back another set of Pokemon but it's not set in stone how many yet.