There is still plenty for nintendo to show at their e3 direct. Remember, Pokemon ALWAYS plays to the beat of their own drum. They want to show off their stuff when they want, and Nintendo lets them. I'm sure their will be other pokemon stuff at e3 as well, but this is probably the big, or one of the big, gameplay info of the game. Show a bunch of new pokemon, the cover legendaries, and some new and/or improved gameplay stuff.

As for Nintendo's e3 direct, there is still Animal Crossing, Luigi's mansion 3, any new games they want to announce, the next smash fighter, Deamon x Machina, Astral chains, and more