The part that doesn't make a whole lot of sense is why would they develop a new FF 22 MP sensor for the 5D Mark III when they just released another FF 18 MP for the 1D x. The difference in resolution between 18 and 22 is so small it's barely worth the cost and effort that must have went into R&D unless one is suited for video while the other for stills, doubt it. On the other hand, if Canon is going to release a FF 45 MP sensor, they must have developed a whole new sensor technology to overcome noise because with the current technology, that thing will be next to useless above ISO 1600.
I agree - does not make business sense to have 3 FF sensors out there. Look ho they recycled the APS-C sensors and 1Ds / 5D mark II