Valve hasn't confirmed or denied it yet, but all signs point to its next game being a hero shooter called Deadlock. Allegedly. I've seen some screenshots and a short video of a tutorial, and I've gotten a look at some of the game's characters. My thoughts rest somewhere between "huh" and "meh." I guess in the Year Of Our Gabe 2024, a third-person 6v6 shooter with MOBA lanes just doesn't excite me.
I'm not saying it looks bad—though the art style honestly doesn't do much for me, nor does its BioShock Infinite-ass ziplines.