Though it would look like /all what it would really be is more like an RSS reader aggregating multiple sources according to your preferences.
A Reddit alternative would naturally form in this ecosystem, with smaller alternative front ends abounding, and take dominance just as Reddit did, but unlike Reddit it would not be able to screw over sub mods etc.
Subs would be truly independent of the front end site, even if they are themselves also front end providers.
It's Distributed Reddit in a sense.... Though in my view it'd be best to make it content agnostic, so it can be adapted to other uses, specifically for a YouTube clone and such.
Really, there's a model where for most it's essentially a Facebook alternative that integrates into thousands of third party forums seemlessly...