I think there is room for non-gamified learning apps depending on the field and how it's intended to be used. A good example is the field of early reading instruction. The best two apps right now IMHO are Reading.com and Mentava, and they take radically different approaches. Mentava is pretty gamified and kids can use it on its own, whereas Reading.com is basically a computer implementation of Siegfried Engelmann's instructional approach. Has to be used with a parent accompaniment, and most of the onscreen widgets are just there to facilitate co-teaching. Both apps are good and seem to be landing with their target markets, obviously the simpler one is aiming at a lower price point.
Poor gamification is a bigger risk than non-gamification done well IMHO. That's where a lot of children's learning apps have failed in the past.