We obviously can't make a definitive confirmation off this evidence, but we now have another clue that the Call of Duty game that Infinity Ward is working on for release in 2019 is Modern Warfare 4. At the very least, the studio seems to be working on something Modern Warfare related. [Update: Confirmation has finally arrived, and the new Call of Duty is Modern Warfare. However, it's not Modern Warfare 4; this is a number-less reboot of the sub-series, rather than a continuation of what's come before. That said, it does feature returning characters, such as Price (with a new voice actor). Here's everything we learned about 2019's CoD.]

The LinkedIn profiles for at least five former Infinity Ward developers show they are back with the Modern Warfare studio. Each of them has a history with the Modern Warfare series. Infinity Ward animation director Mark Grigsby worked on the first two Modern Warfare games, as did game designer Alex Roycewicz, multiplayer design director Geoff Smith, and studio art director Joel Emslie. Infinity Ward founder Zied Rieke--who left the company after working on all three Modern Warfare games--has returned as gameplay director.

All five men have had lasting impacts on Call of Duty. Grigsby helped define Call of Duty's weapons, even creating the popular knife melee attack in Modern Warfare. Both Roycewicz and Smith designed some of the franchise's most memorable multiplayer maps, such as Modern Warfare's Overgrown and Wetwork. Emslie designed some of the more noteworthy characters and items in Call of Duty, such as Ghost and the ghillie suit. Rieke had a huge effect, being the one responsible for designing the original team deathmatch spawn logic in the first Call of Duty and the flashing regenerating health system in Call of Duty 2--both of which continued to be implemented in and influence many Call of Duty titles.

Prior to taking on their current roles at Infinity Ward, each of the five were contributing their talents to other games. Grigbsy, Roycewicz, Smith, and Emslie were all at Respawn, working together on Titanfall and Titanfall 2. Rieke was at Respawn during development of Titanfall, but then went on to found Darwin Game Studio in 2012 and then join Naughty Dog in 2013 before returning to Infinity Ward.

Infinity Ward is the developer behind 2007's Modern Warfare, 2009's Modern Warfare 2, and 2011's Modern Warfare 3. It's long been suspected Infinity Ward would be the next developer to release a Call of Duty title, as per the pattern of studios working on the franchise. That's now been confirmed (the Call of Duty game the studio is working on is even already in a playable state).

Rumors that Modern Warfare 4 would be the next Call of Duty game first surfaced when Infinity Ward senior communication manager Ashton Williams dropped a hint pointing back to the series. However, neither Infinity Ward or Activision has provided more than hints as to whether the rumors are true.

Activision has normally unveiled the title of each Call of Duty game in May, so we might be getting some form of announcement soon and then further details and a gameplay reveal at E3 2019. We don't know much about the new Call of Duty other than that it will include a traditional single-player campaign, unlike last year's Black Ops 4. Activision has also confirmed the game will have a "huge expansive multiplayer world" and "fun co-op gameplay." Given that Call of Duty has enjoyed a wealth of multiplayer modes in the past though, ranging from the objective-based Zombies to battle royale Blackout, these descriptions could mean anything.