It'd be great if they did. I love all their games so far. Still hoping Rodea Sky Soldier gets released.
Prope is just a developer not a publisher. For a sequel to happen some publisher would have to agree to it - which is possible. It sold decent in Japan and would no doubt sell better on WiiU (with a growing base) I believe Namco published in Japan. XSeed published in NA and they have zero marketing budget. So someone bigger would have to pick this up for any chance of real marketing.