I can't believe this topic hasn't been made yet, so I guess I'll go ahead and do it. What do you want to see in terms of rivals this time around? Should it be multiple rivals, like in Black/White, or a single rival like previous games? What should their motives be?
Me personally, I hope they go back to the days of Gary and Silver, in having an actually rival. Pretty much all of the ones we fought since then were more like travel companions who occasionally battle you. It would be nice to have a rival who really opposes you. You're not friends with them, they don't occasionally give you things, they think they're superior to your character.
The "travel companions" we've gotten take away the sense of a lone trainer against the world, that one felt with the first two gens.