Call of Duty accounts have added the option to link up with Nintendo Accounts, and it could be a sign of Switch-related developments for the series - possibly even some form of Call of Duty: Modern Warfare or previous titles coming to Nintendo's home-and-handheld console. It doesn't mean too much by itself and neither Nintendo nor Activision have made any mention of making a Call of Duty for Switch, but it's enough to start the speculation back up again.
Reddit user maherfawaz pointed out the discovery, which comes in two parts on the official Call of Duty site. Part 1 is a hidden section of the login page code that includes a link to Nintendo, invisibly nestled between the Xbox and Steam buttons. Part 2 is a not-hidden-at-all box for linking your various console accounts from within your Call of Duty account settings - here's a screenshot of what it looked like after I linked up my own Nintendo Account.
That is specifically a Switch logo, though there aren't currently any Call of Duty games for Switch. Does this mean that Switch will get a Call of Duty game soon? It could, but this isn't the first time Activision has added options for linking a Call of Duty account to a Nintendo account out of the blue.
Back in 2015, Call of Duty players noticed they now had the option to link their CoD account with their Nintendo Network ID, the now-deprecated account system that Nintendo used for Wii U and 3DS. Both Call of Duty: Black Ops 2 and Call of Duty: Ghosts were available on Wii U, but they pre-dated the addition of this account feature by several years. As far as I know, nothing else ever came of it. That could end up being the case for these new signs pointing to Call of Duty on Switch as well.
If Activision does start bringing any of them over to Switch, it should start with some picks from our list of the best Call of Duty games.