I've thought about this, too. I don't know if you could sustain a company on this idea. The profit margins on consumer tech are miniscule, and if you do it well, you will have very few repeat customers. But I think it could do well as a one-off Kickstarter thing, if you have the knowledge & reputation to back up your claims, or in small, infrequent batches. Buy a bunch of flat panel displays, slap 10 HDMI ports on the back; an optical audio out; and TV tuner; write up some extremely fast and barebones software to switch inputs. Market it to gamers and tech nerds like us. Hell, open-source the software and make it easily upgradable. I dunno. I think it could work.
You might do better with a modular system. A single port on the display, a separate box that handles rapid switching and HDCP. HDMI switch boxes exist, but they seem to forward HDCP responsibility to the display, so switching is still slow. A broadcast quality switch/crossfade box would rock.
