The Overwatch Anniversary Update arrived only a week ago with a whole bunch of cosmetics and dance emotes to mess around with, but it would appear that is not all we will be seeing this anniversary. As is tradition when revealing something new, Blizzard has just posted an incredibly enticing image onto their official Twitter, and then conveniently left out all of the important information.
As you can see on the image above, the Overwatch devs are clearly teasing more details about the fate of the Horizon Lunar Colony. From what we know so far the Moon colony was used to conduct extensive genetic modifications on gorillas with the intent to make them more intelligent, as seen in Winston. However, due to an event that have very little details about, the gorillas staged a rebellion and either killed or threw out all of the humans, leaving the Horizon Lunar Colony currently occupied only by sentient, super-intelligent gorillas.
In other words, if this teaser is pointing us towards the identity of a brand new hero, I think its safe to assume that Hammond is going to be one of the previously mentioned gorillas. But unlike Winston who was essentially the 'nerdy' one among them, Hammond might be more offensively orientated and perhaps even the mastermind behind the whole rebellion as Blizzard is unlikely to use a random nobody as their 25th character.
The second option is that this is a teaser for the Horizon Lunar Colony map, given that its about time we solved the whole "super-smart and potentially evil gorillas ruling over a giant moon base" problem. Overwatch developers have previously stated that they are messing around with low gravity and other factors in an effort to create interesting maps, so even though they might never implement such features there is a chance they could've been working on a Moon map for quite a while now.
Whatever the case may be this is certainly an interesting development, and I am definitely excited to find out more! Personally, I would prefer it this teaser was for a brand new gorilla hero, ideally one that's focused around fast-paced melee combat with lots of jumping around. Smacking people over the head with Reinhardt is beyond enjoyable, so to have a hero focused entirely on that without the need to constantly hold a blue rectangle would be even more fun to mess around with!