If you want to hunt vaults with friends on Borderlands 3's launch date, you'll want to make sure you're all on the same page. Gearbox CEO Randy Pitchford confirmed on Twitter that Borderlands 3 will not launch with cross-play support.
In response to speculation that today's teased "celebration of togetherness" would be an announcement of cross-play support for Borderlands 3. (It was ultimately just another Borderlands 3 trailer, though it did somewhat ironically emphasize Vault Hunters working in cooperation.)
In response, Pitchford tweeted to say that it was not about cross-play, but that Gearbox is "committed to supporting cross-play for Borderlands 3 with our partners as soon as practicable after launch." In a follow-up tweet, he further clarified that there will not be any cross-play functionality in Borderlands 3 at launch, but they are committed to cross-play on "as many platforms as possible."
This is an odd contrast to April 1, when he noted during a Twitter response thread to Borderlands 3 being an Epic Games Store exclusive on PC that "we believe multi-platform support is a pre-requisite," so it's unclear what could be holding things up. To get further clarification from a site that isn't Twitter, a 2K spokesperson told GameSpot in April that "cross-play is something is something we're looking at closely, but we don't have anything to confirm or announce at this time."
So crossplay hopes for Borderlands 3 are back where they started: in a nebulous state of uncertainty. You can at least probably not expect it in time for launch on September 13, for PC, Xbox One, and PlayStation 4. If you want to get an idea of what Borderlands 3 is like, and particularly how it's echoing ideas from series like Mass Effect, check out our preview from May.