Gearbox Software's Randy Pitchford has made it clear that Borderlands 3 is not presently in development.
"We love Borderlands, and we know customers do too. So we will be doing more in Borderlands. But the thing that, when you think of what Borderlands 3 should be... No. We are not developing that right now. We don't know what that is yet. We can imagine what it must achieve, but we don't know what it is yet. I'm not going to fuck around with you like Valve does with Half-Life 3. Look. We know we want it and we know it should exist, but we don't know what it is yet. But we are doing things in Borderlands that we'll announce soon, that are good, and that I think people will be really excited about if you love the franchise."

Pitchford was also quick to mention that there will be more Borderlands by way of the Tales of the Borderlands from Telltale Games. He's actually really excited for that one, being a fan of their current work in The Walking Dead and The Wolf Among Us.

Pitchford's interview with Polygon goes on to talk about some of Gearbox's other current developments. These include Furious Four, Homeworld, and more.