Even with all the controversy around your numbers, I have to congratulate you by doing your estimations with a solid method and detailing the decisions you made in the process.
I agree that the difference between PS4 and One will widen. Right now, we only saw early adopters, that are pretty much price insensitive consumers, buying units. When these guys are done, and it's happening now, we will see the mass market that cares about pricing.
About your considerations of market size, I agree with you, market won't shrink. It would even throw if it wasn't by all casuals Wii got in 2008-2010 and lost to mobile. We saw the two biggest launches in history and that was for consoles way more expensive than the normal 300 dolars gold spot. Besides that, consoles are more mainstream now and emergent markets like the BRIC countries, that were always lagging behind in console adoption, now will be at full force buying these new devices.