Seems like a sensationalist headline designed to generate page-views. The company has not announced it's "for sale"; instead people are reading between the lines and coming to that as a conclusion based on corporate speak.
But I think what the people are reading between the lines is "if you decide to buy the majority share we will cooperate".
If Yahoo gets rid of the stakes in Alibaba and Yahoo Japan, then YHOO would properly reflect the value of core Yahoo, and someone with a few billions lying around could gobble it up.