It's the site This Gen Gaming to launch the news that many of you, probably, were waiting for. The site in question is "discovered" that Borderlands 3 can be booked online by UK retailer ONLY for PS4 and Xbox One at the price of 55 Euro. The release date, however, is not indicated.
So we do not talk about rumors properly: the game is actually in pre-order and if you're so lazy to go check it out, I put a screenshot here below.
Borderlands 3

It is also true, though, that the game has not yet been officially announced by chicchessia. Nevertheless, there is a very important event that could complete the puzzle and make the possibility of an official announcement at a least likely:E3!
The assumptions are all, including considering the release year of Borderlands 2 (2012) and Borderlands: The Pre-Sequel (2014): as time is right.
We resound during or after E3 for possible (and probable) novelties. Pleased ?!