Well, what can we say? If we happily ignore Wii and if we gleefully bash PS3 even when it's starting doing well and if we deny that costs reduction happens, starting from a higher initial value, obviously, at the same % pace as the others (and even faster for new optical devices that suffered from high prices and shortages of blue lasers at the beginning, being quite a novel tech), and if we finally deny that even the third ranking console becomes appealing for most games developers when installed base exceeds 30M, then yes, XB360 rules and will rule forever.
Sadly for MS reality is quite different, it can thank Sony's initial clumsiness and overconfidence, PS3 excessive price, initial blue laser shortages forcing a scattered world launch with a EU delayed to Easter launch much smaller than it could have been on the previous Xmas, if it still keeps its 2nd WW and USA place, but it totally wasted its lead letting Wii surpass XB360 in a few months.
Oh well, this doesn't even matter, Wii rules almost all casual and the whole nintendocentric hardcore, and always will do for the rest of its life, but as this gen grows older, PC will rule more and more the not-nintendocentric hardcore segment, 2010 and part of 2011 will see the peak for HD consoles, then PC will be back on top, it's always the same pattern each gen.
As PC means Windows, MS could be in theory happy anyway, but as long as 32bit lives, most PC gamers will prefer the old XP for its lower resources consumption, good stability reached and smaller amount of quirks, damaging newer Windows version sales, as Vista's relative flop teaches us.
Not to mention that MS grabs royalties on XB360 games, but not on Windows ones, unless they use licensed MS tech.