I have a feeling this is probably old, but I haven't heard anyone else mention it, so I thought I would in case someone hasn't noticed.
In the demo footage, you can see that as usual, opposing trainers usually use Pokémon that match their gender. For example, notice that Professor Sycamore uses exclusively male Pokémon. The exception has always been when a Pokémon has more than a 50% chance of being a particular gender, in which case trainer-owned Pokémon will always be of that gender (for example, trainer-owned Vulpix are always female, because Vulpix has a 75% chance of being female). Because of this rule, all trainer-owned starters have automatically been male, even when used by female trainers, because they have a whopping 87.5% chance of being male. However, in the demo footage, Serena's and Shauna's starters are both female. This means that there is a possibility that the new starters have an even 50/50 gender ratio.
Of course, this being a demo, we can't be positive that this reflects the way it will be in the final game, but I thought it was still pretty interesting.