In an interview with the Official Xbox Magazine, Zenimx Online's Matt Firor has confirmed that the studio is working on a new project, but doesn't divulge much more info than that. Thanks to WCCFTech for the find.
Not a lot of people have picked up on this, but if you look on our job site you’ll see that we are accepting applications for people to work on a new engine for a new triple-A game. So yes, we have ideas, but we’re committed to ESO for as long as it takes.
My "what could it be" wheels are already spinning. I don't think it'll be a Fallout Online title, despite wishing it would be, thanks to the launch of Fallout 76. My gut says it's a new IP, and likely a cross-platform title to boot. Whatever it is, I'm kind of hoping we don't hear much about it until it's just about ready to launch. I appreciate that Bethesda has taken that route with most games these days, as the hype doesn't drag on too long.
So, will it be an online shooter to pick up the slack EA's Anthem has left behind? We shall see.