>>30293727They're never going to do it.
Think about it. That'd be too much work for them to do. They've always ran on the idea of a lot of stuff being unavailable in one game so that makes you buy the next set of games, whether they're sequels or third versions or remakes of past games. Can't get all the Mega Stones in Sun and Moon? Tough luck, wait for the next game and hope that it has them.
Game Freak isn't the kind of company to update their games. They've made their money on locking content out and hoping that dumb players would buy more games to alleviate that supposed issue.