Honestly I would look toward manufacturing, particularly if you can incorporate ideas from the world of the digital -- for example crowdsourcing, mass customization, or continuous delivery of updates/modifications. I read an article in WIRED oh, I guess about five years ago now, called "Atoms are the new Bits" that talked about companies using 3D printing, crowdsourcing, etc, but to make real world products.

Part of the reason I think this area is hot is that it's harder to do than apps. Every "app" I can think of has already been done, and in fact there's probably a dozen versions of it languishing in app stores. Manufacturing is harder, and is often geographically local, so there are fewer competitors and more niches.

Another leading indicator for me is the general rebellion of young people against the fact that "shop class" has been taken out of schools. Lots of kids are trying to find ways to be "makers". In my state, when I was in school the "dummies" were pushed toward taking vocational classes in plumbing, welding, etc. Now (20+ years later) the vocational classes are the most competitive, prestigious classes that students fight to get admitted to.

If I had to guess, the new manufacturing is going to be smaller scale, extremely high quality, locally sourced materials, with some kind of digital "twist" on the business models.