I’m pretty sure they announced Smash in the last direct so they can use it as their Spotlight title for this year’s E3. That dosen’t mean they can’t announce something huge during their usual direct and use the Treehouse to focus on said games. Games like Fire Emblem or Animal Crossing can be unveiled during their online presentation and have gameplay showings on the floor. They’re big titles, but they don’t need to be the main focus to be successful.
As for Pokemon, I’m pretty sure we will have an announcement and a small glimpse, but the main push will be made by the Pokemon Company, not Nintendo themselves.
I expect some 3rd parties to be unveiled by Nintendo, but mainly the ones we are waiting for, like GTA or Fortnite, but the rest will be handled by their respective publishers at their own events.