I just read the sequel is planed for 3D theatrical release on July 18, 2014. Maybe planes will be in Disney Infinity 2. Disney Wikia says that it will be a trilogy .
http://disney.wikia.com/wiki/Planes:_Fire_and_Rescue John Lasseter said: "I kept thinking about—I’m a big train fanatic. I love trains. And I started thinking about trains, and boats and airplanes. And I kept wanting to have more and more of those type of characters. [...] It’s one of the ideas, that there will be an ongoing series. It almost starts getting into this thing where we fall in love with these plane characters, we want to see more and more stories with them. And then you start doing other vehicles and stuff like that. Yeah. So it kind of is a bigger idea that can keep expanding."