The two way bookshelf stand mount or floor standing design is probably the most saturated format in the speaker market. If the goal is to make a living in making speakers, one has to stand out from the rest by offering something that is so different that it at least piques the curiosity of some of the audiophiles to give it a listen. At the minimum, you should be willing to allow for in-home trials with expectation that the customer will be so blown away that they not only keep the speakers but also solicit friends to give it a try. I’m a firm believer that if the product is a good value, it’ll catch on. But it has to be really really a cut above everything else out there and to me that is probably the biggest challenge. You can start with the audience here and ask how many are willing to participate in (and support) your venture. Just as one data point, I've been smitten with the sound of single driver full-range speakers and have studied at least a dozen of designs all spread across my desk. Yesterday while looking in the used market, I saw an add from a guy who had built a custom full-range speaker with excellent cabinet - used 3 sheets of 3/4" MDF pressed and glued, veneered professionally, and used Fostex F200A drivers @ $700 each, custom stands, custom crossover, asking $1500. I could not even come close to building something like that and expect to make profit.