In an article published this morning, Eurogamer says it has sources who know what's going on with Call of Duty this year. According to those sources, this year's Call of Duty is named directly after the setting of many-a-Call of Duty before it: Call of Duty: WW2.
As is well established, Call of Duty now operates on a cycle of three development teams, and 2017 sees the newest among them, Sledgehammer Games, cycling back into the spotlight. The last time Call of Duty riffed on the "World War" theme was 2008's World at War, while Sledgehammer itself was responsible for 2014's Call of Duty: Advanced Warfare.
As Eurogamer points out, it didn't technically break the story: images of the "WW2" branding appeared last week on YouTube, albeit unverified (see above). With it's report today, Eurogamer claims to have verified this information, and given their recent track record essentially confirming that the Nintendo Switch (then the NX) would be a hybrid device, there's little reason to doubt the information.
The latest Call of Duty developments are hardly out of left field – Sledgehammer founding member Michael Condrey noted around the time of his studio's last CoD release that he feels "a next generation game with the latest production values and robustness in a World War II setting like Band of Brothers would be amazing." Well, if today's revelations are true, then it sounds like Condrey is getting his wish.