I think Reno is more on point with his classified breaker comment. As long as they only sell breakers and the breakers are only allowed to be used in their panels by abusing 110.3(B), they have an assured market in new load centers.
The 2011 change assures this.
If I was an enterprising entrepreneur I would make a small panel, intended to be used as a sub that was listed with an aftermarket breaker.
I suspect the problem is there is not enough profit in this to cover the cost to get it listed.
