Pandora's fate is out of it's hands, but in the hands of the government. The current royalties it pays are not sustainable. I'm sure all are aware of these rates but for any who are not, P pays ~60% of revenue in royalties, satellite radio/cable radio ~10-15%, and traditional radio ~2% (however no performance royalties). The current market is extremely unfavorable to internet radio.
The Internet Radio Fairness Act attempts to reduce these royalties, but with the fiscal cliff and with little support/publicity, it is unlikely the bill get's passed in the near term.
The service is however extremely popular and revenue and users are increasing very quickly (however, due to the current system, royalties will increase step in step with listener growth and therefore the current model is arguably not sustainable). A purchase by google or facebook would be highly accretive as the ads could potentially be much more valuable as currently Pandora knows very little about its users, great product but a broken model, a very tough investment decision.