Last week, Helldivers 2's game director Johan Pilestedt revealed that eight-player teams are being considered, but they won't be implemented anytime soon. However, a little later on in the thread, Pilestedt also made a reference to a Helldivers 2 sequel - although not in the way some fans may have expected.
In a tweet, Pilestedt says that the team is "growing Helldivers 2 into Helldivers 3". This was in reference to an update that could add an eight-player mode, suggesting that Arrowhead is more concerned with adding new features to Helldivers 2 than working on a full sequel.
This was in response to one fan, Twitter user @samarialainen, making a joke about a possible sequel: "Helldivers 3, coming in 2032 will add 8 players and swimming".
In a reply, Pilestedt reveals that they "may be correct" - apart from swimming coming to Helldivers 2. "I don't think it's possible to swim in a heavy plate carrier with rifle and support weapons," the director replied. "Also, all our games have had the thing about the protagonist not being able to swim."
While this is just a jokey reply to another jokey tweet, it could give us some insight...