I was thinking about that the other day.
There are so many hubs/cogs/lockrings manufactured to standard track specs that work well on the street when properly maintained.
it would be tough to compete with what's out there.
level tried to do the whole bolt on cog thing... it's a great idea but i don't think they saw (or are seeing) much success.
I think it's a great idea that could have a following if it was sold at the right price, but it will never sell the same volume as the current standard track stuff.