I think that you can look around and see by the deficiencies in every manufacturer's products that there is room for someone to come along with better ideas and better execution. Among my favorite three housing makers, I don't care for Nexus's wide angle ports and bouyancy, Subal's 1/4 turn bayonet and excessively heavy plastic port construction, or Seacam's poor manual focus implementation for macro. Of all the manufacturers, it seems to me that Inon is innovative with their magnetic manual focus control and integrated wet diopter mount. Underwater photographic equipment is a small industry and, it seems to me, that's where the barrier to entry isn't overwhelmingly high. I doubt anyone here can advise on the best way to profitability. If they can, they're probably not talking ;-)
If it were me, I'd concentrate on foolproof servicability, bouyancy, good ergonomics for wide angle and macro, autofocus and manual, and improved optics. There are opportunities to improve both wide and and macro optics, wet diopter solutions are poorly implemented, and there are no really interesting macro lighting products. I would concentrate on fiber rather than electrical for sync cords and consider ways to leverage manufacturer's TTL better than what is being done today. Frankly, I think a housed Nikon/Canon land strobe should be very interesting but not when it's put in a 1/2 gallon plastic jug.
Why can't we figure out how to create a macro lighting solution that converts from a ring flash to a conventional flash during the dive? Why can't we have a wet diopter that doesn't go from "not enough" to "ridiculously too much" without having crappy image quality or weighing a pound underwater? Speaking of weighing too much, how about a magnified eyepiece that doesn't upset the balance of the rig? We can do better.
I'd like a macro port system like Inon's with a magnetic focus ring and integral wet diopter mount but I'm not sure 67mm diopters are good enough. I'd also like a integral ring flash option, preferrably one I could dismount underwater for shooting subjects further away. I'd also like to eliminate sync cords and have foolproof TTL. I'd like a grip that's not designed by someone who's never used a camera underwater; one that I can use to pass my housing one-handed up to a boat without it spinning in my hand! I'd like a macro focus control that actually exists where my left hand is when I shoot and focus, shutter and control knobs all easily controllable without hunting with my right hand. I'd like a good modeling light, possibly integrated with the ring flash. I'd like a powerful, broad wide angle strobe that can be filtered, diffused, powered by AA batteries and triggered by fiber. I'd like wide angle ports that are sharper at the edges than we have today and macro ports that are free of chromatic aberrations.
