I believe they know better than you do about that (bold) :)
More marketshare = more game, live, accessory sales = more money at the end...
yet MS hasnt turned a profit on the xbox in all these years with all the R&D cost and losses on system, not to mention the blunder that was RROD, its the reason they took losses from 2001-2010 and only started making money on it in the last 4 years and with the xbox1 pricecut, and free game deals and whatnot im sure they are taking a loss again. the rumors about spinning the brand off or selling it im sure will come back.,
You are talking like the brand means nothing, you know in the big picture it is important to count that too. The value of the brand itself is enough :)
You realize Sony did lose a LOT of money on PS3 like Microsoft with the 360 for instance and I do not see them spining off the Playstation division. The brand worth a huge pile of money.
Microsoft is investing in Xbox because the brand is now very well know. Microsoft will never let this go as one of their priority is to be the center piece of the living room. If Xbox One will not meet their expectation in that area, they will at least have build a good footing for the next generation. Not to mention Xbox Music, Xbox Videos etc...
You must look at the overall picture.
And as far as the rumors... They are exactly that: rumors.