Well, GO has arguably brought it back. ;)
However, the main games are probably a lost cause at this point. The main series hasn't had anything close to mainstream appeal since (at least) the DPP era, and it's reflected in the way that the games' sales have done a Titanic impression since then.
Gens 5 and 6 appealed far more to veteran fans than new fans, and for better or worse, a franchise like Pokémon needs fresh blood to stay afloat. Appealing to older fans in Gen 6 got Pokémon completely destroyed by Yo-kai Watch in Japan.
If Gen 7 is giving off "reboot" vibes, this is likely why. GF is trying to win back the kid audience from Yo-kai Watch, although it remains to be seen how successful they'll be.
I think a lot of it goes back to Shudo. He wanted the anime to be a smarter series that could appeal to people of all ages, and he notably hated the direction the show started taking in the Johto arc. Nintendo, on the other hand, never saw the series as anything more than an advertising tool for little kids, and suffice to say, they won. :rolleyes2: