Fans have been crafting theories for a while about a potential Baldur's Gate title in development, with most fantasizing about the game being done by Larian Studios, and then Brian Fargo tweeted about it. So let's untangle this info mess.
Considering the mass success Larian Studios had with Divinity: Original Sin and Divinity: Original Sin 2, it's no wonder that fans hoped they would be the studio behind the next Baldur's Gate title. Unfortunately, this will not happen as Larian Studios have confirmed that they are not working on a Baldur's Gate title and they didn't purchase the IP in order to work on such a game. On top of that, the studio's full attention is on Project Gustav at the moment.
The fact that they weren't working on Baldur's Gate 3 threw many fans in despair as they gave up hope they would see another entry in their beloved franchise. This may not be the case though, as Brian Fargo tweeted that he "knows who is working on BG3".
To connect the dots for gamers that might not remember the ancient history that happened some 35 to 20 years ago, Brian Fargo is one of the founders of Interplay, which had a subsidiary named Black Isle Studios that happened to be the developer of the original Baldur's Gate.
Some fans may have misunderstood Fargo's statement for a confirmation that Larian was working on the title, which prompted the company to release the aforementioned statement where they denied any connection to the IP.
That said, it still defnitely sounds as if Baldur's Gate 3 is in development, and it probably wouldn't be too long a shot to guess that Beamdog is working on the title as they have previously released the Enhanced Edition of the original game, as well as a new expansion, titled Baldur's Gate: Siege of Dragonspear, which is the only original content Baldur's Gate series received in over 15 years.
Still, there is no official confirmation from any studio about them working on Baldur's Gate 3, so any guesses and derived info should be taken with a grain of salt.