[whirlycott1]

It's a venture funded business. There are only three outcomes: sell, go public or crash. What were you expecting?

They also said their API will stay up:

http://blog.echonest.com/post/78749300941/the-echo-nest-join...

[untog]

...sell to someone that isn't Spotify?

[JangoSteve]

Any company that has both the economic ability and incentive to acquire The Echo Nest would have the same potential to be one-sided in their acquisition as Spotify.