So, bolt on and LeveL style interfaces have not caught on mainstream for a couple reasons...LeveL's is proprietary and bolt on is mostly a homebrew workaround (and a great one at that).

What could catch on quickly if a particular company decided to push it?

Well, Shimano is doing fairly well popularizing the already standard cassette spline cog for singlespeed use in BMX!



All we really need is someone to cut splines into a normal track hub. This shouldn't cost anyone making hubs more than the threading they do right now.



This is so stupid-obvious, why isn't this the standard?