I'm thinking Ana is Sombra, because her Shrike skin looks exactly like Sombra, but who knows.
Nah, Shrike isn't Sombra. People only assumed a lot of stuff about Sombra and what turned out to be Ana, partly because they thought Blizzard would only tease one character. The file in Temple of Anubis with Ana's Shrike helmet and the Gamespot documentary "leaks" were the only direct hints to Ana.
While everything in relation to Sombra is completely tied to Dorado. The helmet with the triangular visor is not at all in the Dorado map, and if you look closely at the newspaper, you'll see that the shadowy figure in it has more robotic legs, while Ana has normal legs with regular boots. Nothing of the Sombra hints in Dorado hint at Ana, and Ana has absolutely nothing that ties her to Dorado, either.
Besides, if Sombra was Ana, then Blizzard would clarify that, and make a clear reference to her being Sombra.
Instead, upon being asked on Twitter, they were being coy about it:
https://twitter.com/PlayOverwatch/status/752943240047759360
(also gold from that Twitter thread
That said, I would love if Blizzard would make an in-game reference to people thinking Sombra was Ana by them getting some dialogue on Dorado/Temple of Anubis or something. It'd be funny.