Sport Shoes
I already use Stridalyzer insoles in my regular sport shoes and find they're great - not only an audio feedback on overpronation or knee stress but post run feedback and recommendations on what stretches and co-exercises to aid correct the damage done in a run or improve form.
I think smart insoles will be a better option than native built into the shoe personally, but I guess we'll see what the (admittedly niche) market of tech enthusiastic runners say - as I don't think it'll go much wider than that, will the average Joe be interested in having the internet of things at his feet?