Many Pokemon fans thought 2020 would see the remakes of Pokemon Diamond and Pearl, but that hope was more or less crushed by Sword and Shield's Expansion Pass. However, a new tweet from The Pokemon Company seems to have lit a fire under those who want to see Sinnoh on the Switch.
April 22, 2020, was the anniversary of the release of Pokemon Diamond and Pearl in North America, so it's not really surprising that it issued a tweet in honor of this anniversary. But closer inspection of it has led many to think it is more than just an anniversary tweet, instead teasing remakes of Gen 4.
There are a couple of things about the tweet that seems off, with the biggest namely being that "Confirmed:" that appears at the start of the below tweet. It doesn't really fit into the context of the tweet and seems like something shoehorned in, which could really only hint at the possible Pokemon Diamond and Pearl remakes. Secondly, the tweet ends with a winky face emoji, which on one hand could be for Sinnoh's Battle Tower and Contests reference, but would also go hand-in-hand with the "Confirmed" mention.
As such, many fans are keen to take this as a legitimate tease for remakes of Gen 4 and think that it could even still release in 2020, perhaps some time after The Crowned Tundra releases for Pokemon Sword and Shield. That said, it doesn't really seem that fans could be treated to a remake of Mystery Dungeon, the Sword and Shield Expansion Pass, and remakes of Pokemon Diamond and Pearl in one year. This tease could be for a formal announcement later this year, with a release date sometime in 2021.
It's really up in the air right now, but even without these tweet, more remakes seem likely. The Pokemon Company has been doing this for some time now, dating back to Leaf Green and Fire Red, and the popularity of the Switch practically begs for more Pokemon remakes to arrive in the future.
Pokemon Diamond and Pearl Remakes are not known to be in development.