As someone who has built & designed custom in-wall sub solutions for customers in the past, I can say there is a market for this kind of product. However in looking at the enclosure, it will not fit in MANY applications. The JL Audio & RBH solutions (amongst others) that are out are much more conducive to this style of application.
Although, I would rather build the sub for the application to ensure the highest level of integration within the space. AND, chose the compromises I want to deal with.