This smells like headline-bait me, but I'll bite. Jordan Rohan, an analyst at RBC Capital Markets, forecasts that MySpace could be worth $10-20 billion in three years, according to Reuters. Rohan came away from a meeting with Fox Interactive and wrote a research note to clients stating, "$15 billion in a few years? It is possible". Although he admits the claim is "audacious", he asserts that it's justified by MySpace's unprecedented growth.
So how did Rohan arrive at the figure? Apparently he looked at the rumored $1 billion Yahoo-Facebook talks (no purchase yet) and the $1.5 billion valuation for YouTube (this number is also baseless), then extrapolated. He also factored in Google's $120 billion market cap, and looked at how MySpace could monetize its audience - direct response marketing, ecommerce and high-price advertising. Whether or not the prediction turns out to be true, most people would agree that this kind of comparative math is fuzzy at best, and a stab in the dark at worst - nobody is buying YouTube for $1.5 billion, for instance. Whether the aim is to bump up News Corp's stock price or get more attention for RBC, I'm not sure, but it seems these valuations amount to little more than guesswork.