Syndicate is a bit of a different case since Evie only appears in 20-25% of the game if the original rumors hold true, which makes me suspect that's actually a case of them seeing the response they got last year and adding her in mid-production.
It will probably become apparent while playing the game if all the important story beats also do not include her.
That is insanely lame. Especially since the word that they've been putting out seems to imply you can play either or and no mention of restrictions.
I don't understand caring about what gender a game's main character it is. The fact that it is a marketing issue is crazy to me.