I agree Xbox is the only thing that gives them credibility in the consumer device world, hence xbox music, xbox video etc plus it now links in nicely with windows 8, I really struggle to believe this, unless the deal is that amazon pay MS to continue to develop the OS side of things
But they make like 98% of their profits from enterprise solutions. Thinking that they need a window into the consumer market is like thinking that some massive, billion dollar security firms that handle trillions of dollars in assets need to get into home alarm systems. They don't. They don't need brand recognition, outside of cellphone contracts enterprise solutions are decided by totally different merits. If anything, MS' diversion in focusing on consumers has left the door open for Google to slid a foot in to enterprise. That scenario is nothing but bad news, as the real bread and butter is being stolen. That's what a lot of investors fear.
Not to diminish Sony, but a nightmare scenario would be MS reduced to a similar level of consumer services and electronics. There's almost no money in it, the manufacturing and development costs are too high to make much profit. Sony makes a ton of income off insurance, let's not forget. Insurance. We certainly don't hear much of that branch either, which shows you how enterprise works. (They offer life, if I recall too, but most of it is enterprise solutions.)
As an aside, I'd be far more partial to an Amazon managed Xbox, than an MS one.