The customer market for Windows is already slowly transitioning away from Windows. I think it's logically to say that if the consumer market goes, the corporate market will fall soon after that. Microsoft could have either ignore this, as Apple continues to sell more and more Macs and iPads or they respond with something to take on what Apple see's as the future of their consumer facing business: the iPad. Microsoft chose the action that might have a chance to actually turn this trend around… Time will tell if it works.