At this point, it's Activision Blizzard's words against leakers, and we're betting on the latter.
Despite the publisher's constant denial, a growing number of leakers claim that Activision is up to something. The most recent insider, TheGhostofHope, reveals that its sources have told them that a remaster of the campaign of the fan-favorite shooter from 2011 is "just sitting there waiting for the right time to be released."
As mentioned, Activision previously denied reports about a Modern Warfare 3 remaster. In particular, a representative spoke to CharlieIntel last year and explained to the publication that "A remaster of Modern Warfare 3, campaign or multiplayer, does not exist. Any reports otherwise are incorrect."
Activision can only blame itself for setting a precedent. In 2016, Activision released Call of Duty 4: Modern Warfare Remastered as part of Infinity Warfare. The remastered shooter had a fully functioning Multiplayer mode and everything. Then, in 2019, a remaster of its sequel, Modern Warfare 2, came out albeit it didn't get a multiplayer mode this time around. When you consider that the fan-favorite Call of Duty offshoot ends with its third installment, you can't blame fans for wondering when the remaster of the 2011 shooter will come out - not if.