The 360 & PS3 both suffered from horrendous stock problems straight after launch though.. they would of both sold far more.. well the 360 certainly. Either way.. with your predictions on how much the Wii U would sell in the first year being absolutely miles off.. I'm pretty sure your guesstimates can be taken with a pinch of salt... the PS4 will easily outsell the X1 at launch worldwide and I reckon they will be more than 500k in it by Christmas. Both consoles will of outsold the Wii U by Easter I reckon
All consoles suffer from supply constraints at launch. Releasing a console is a logistical nightmare, pretty much everything is done at the last minute.
As for outselling the Wii U by Easter you're not taking into account the software on the way. The ridiculous software drought is over at the end of this month. July - Pikmin 3, August - The Wonderful 101, September - Wii U Play, October - Wind Waker HD, November - Donkey Kong and the two big guns in December - Super Mario 3D World and Wii Fit U.
The Wii U having an installed userbase over 8m before the end of the year is very doable - 4m sold already, 1m between now and 31st October and 3m between 1st November and the 31st December.
Sony and Microsoft won't be able to ship more than 2m consoles each, let alone sell them. And you're forgetting about another very big gun being released in April - Mario Kart 8 - which is going to give the Wii U a nice sales boost, even if the likes of Yarn Yoshi, SMT x Fire Emblem, X and Bayonetta 2 aren't released before then to keep sales momentum going after the New Year.
It's going to take years for Sony and Microsoft to catch up, just look at how much an advantage just a 5.5m lead a year's head start gave Microsoft with the 360 last gen. The Wii only overtook it because it was a ridiculous sales phenomenon and I can't see the PS4 or One emulating that sort of success.