I don't think so. I don't think they will break this tradition.
Besides, thinking about why Pokémon games have 1 save file per cart, I'm not sure I want this. Scratch that, I'm sure I don't want this. Every time you win against a trainer, pick up an item or complete a side mission, it adds to the size of the save file. Pokémon themselves take a lot of space. It's basically either you have one save file and a big Pokémon game with lots of stuff to do, which is the case now, or (insert number here) saves and (the same number) times less trainers to fight, items to pick up, side quests, boxes in the Pokémon storage system etc. With each generation becoming bigger and better, emphasis on the "bigger", having multiple save files with all the repercussions would severely handicap the game.