It’s very unlikely that Borderlands 3 (or whatever the official title of the game will be) will come to Nintendo Switch. A recent tweet made by CEO Randy Pitchford seems to confirm this notion.
When asked by a fan on Twitter about the possibility of Borderlands 3 coming to Switch, Pitchford said, “I do not see that as happening. We were talking to Nintendo, but that stopped for some reason. They have other priorities.”
In April 2016, Pitchford confirmed that Borderlands 3 was in the works at PAX East. “Obviously, there is going to be another Borderlands,” he said at the time, explaining that it may not be called that, and to not get too attached to the name.
Borderlands 3 was initially announced in January 2015, and Pitchford referred to the game then as “the big one.” Parent publisher Take-Two later clarified this game is being developed “specifically for next gen” meaning it will launch for PS4, Xbox One, and presumably PC as well.
As to what Nintendo’s other priorities are, we may never know for certain, but this is a huge year for them nonetheless with the release of the Switch.