We'll, we should be getting New Pokémon Snap (hopefully with a new name) in 2021. Based on the visuals we've had, it would make a fun Northern Hemisphere Summer game (I live in Brazil, but even winter is usually warm, so...).
And they could have a new game for the holiday season, or the gen 4 remakes.
But I wonder what would be more surprising. It would be absolutely amazing if they added GB to NSO and Pokémon Red and Blue were a part of it and connected to Home, but that makes little financial sense to TPC. So I'd guess they could released the GBA games throughout the year on the eShop for $10 to $12 each and make bank.
There's also The Pokémon MOBA and the poorly explained Detective Pikachu game (is it an updated upgrade or a brand new game?).
But we'll likely be getting A LOT of Pokémon stuff in 2021