Overwatch was and we were all speculating it was some sort of expansion based on the fact that the trademark had been filed? Oh, it was a more innocent time. Unfortunately for that trademark, it might be having a little bit of a problem after all, as it has come to light that another company filed an earlier claim for the trademark that would supersede Blizzard's use of the name due to likelihood of confusion.
The trademark that has already been filed is for an app that can be used to provide enhanced functionality for paintball matches, laser tag matches, and the like. Both trademark applications are currently suspended pending investigations, so it remains to be seen whether Blizzard will be pushing forward or will change the name of the game to something legally different. Like Oversupervise, for instance.