I would say even two out of three of these would appeal to different end users (depending which 2) and increase their popularity. For a concealed handgun, basically size is my issue. I find it ironic when people put a dot on top of a micro 9mm (43, 365, etc). If I'm going to add that kind of size to a small gun, I'd rather just a bigger gun and forgo the optic. In other words an iron sighted G19 is more appealing to me than a 43 with optic (even if capacity wasn't an issue).
Now the true game changer would be some kind of holographic emitted sight (think Star Wars like holograms - "help me Obi Wan Kenobi"). The emitter could be embedded in the slide, adding no bulk and be totally protected from abuse. Is it possible with future technology? Who knows, but imagine explaining an iPhone to someone in 1980.