Let me introduce you to The Magic World of Game Freak and Pokémon:
Game Freak basically releases one main series Pokémon game EVERY year for about 3 Years every time, after that there is a one year of pause because such a development one after the other kinda compromises the quality of Games so to keep a relatively high quality they decide to take a break, Sadly you can notice that in Pokémon ORAS, beeing the 4th (IIRC) game in the 4th year , which while it's in the same generation of X/Y has worse graphics and lacks of content (aka Battle Frontier aka MegaFlygon cuz they didn't even have the time to think about a concept for making it).
So as time goes Game Freak's development team grows as well so that in future they can handle more and more new games year after year. indeed In the next "stock" of years we could see Pokémon Z, the 3/4 titles of VII° (with 2 releases), a Remake (probably Kanto) and maybe even the beginning of VIII° gen









