I personally am greatly disappointed in the number of new Pokémon. I mean, look at the generation pattern.
150, 100, 135, 107, 156, 72
There has never been less than 100, and that's how it truly should be. 100 is the absolute minimum. To me, the Megas are nothing but glorified Forme changes. It's evolution that isn't permanent, which means they do not count as 'new' Pokémon.
My theory? They will have the "Pokémon Z" of the generation, whatever that turns out to be, and they will introduce more Pokémon that are genuinely new, maybe a few more Megas, and some more actual evolution connections, so Sylveon doesn't have to be the only tie to the older Pokémon. The reason there are more older Pokémon in the Dex, isn't just t balance it out. I feel that certain Pokémon are in the Dex, because they either have a Mega Evolution, or they are Pokémon with potential for an evolution connection
It'd be a first to spread out the Pokémon among the games, but it'd work. Reveal and release the slow way, so that, by the time they're ready to begin Gen 7, Gen 6 will be complete and have 100+ Pokémon, as it should, to maintain the pattern.
Sure, there's still Hoopa and Volcanion, but that's normal to reveal the "hidden" legendries with each movie. But they also still need to give Zygarde a movie. So I figure, by that time, they will be promoting "Pokémon Z" and hopefully introduce more new Pokémon along with it, and maybe even an alternate Forme for Zygarde
Over the years of me being a dedicated Poké addict I've kinda developed a knack for predicting things like this, and most of the time, I am proven right