I always wanted to create a social app for shoes and call it Sole Mate. Put in your specs and rank your own shoes and then find other people who have a similar fit to you and see what they liked.

Sounds like it could be an amazing feature for Zappos - "you picked this shoe at this size and didn't return it, here's what others who did that also bought".

Ive seen Dr scholls in-store kiosks that do a mapping of feet to (i think) create custom insoles. It would be cool to have a digital file of not just a 3D impression of your feet, but also some data related to pressure distribution related to gait that could (in theory) find an optimal shoe (not objectively optimal -- but aligned with others that have similar characteristics).

And presumably as your weight changes you would need new models.

Heck I'm surprised there aren't more "smart shoes" that track weight changes and mobility.

Not exactly what you are describing but there are some sites like runrepeat.com that are basically a database of running shoes that let you compare stats and check aggregated reviews on whether they fit true to size etc along with reviews for some of them. Before I found that site it's was basically a crap shoot to figure out the subtle differences between seemingly 50 different models of slightly different shoe from each manufacturer but that site really helps me narrow it down and find similar shoes to stuff I already like.