It's very hard to tell, really. While Kalos hadn't given us much new Pokémon, they were still quite busy perfecting their mega-evolutions system and coming up with designs. While mega-forms are just basically... well, forms, they still do have different appearance, and for some, they could be seen as some new Pokémon as a whole. To me, though, they're not (their still relatively same, aside from looks and stats), but they do count for something.
Will this how the pace will be for future gens? It's kind of hard to tell. If they're aiming to give us more megas in generation seven, I don't believe they'll be putting much effort into new Pokémon. If it's vice-versa, then yes, they most likely will.
Personally, I'd like them to keep it all slow, like how it is now. There are a lot of Pokémon out there, and the more you add, the tougher it becomes when you're trying to complete your PokéDex. Although it isn't mandatory, some do attempt nonetheless, and because of quantity, many of them lose motivation mid-way through and quit. If it weren't for that, a wider range of people would've been successful, I'm sure.