Why do you think dropbox is unlikely to find an acquirer? Because they're too proud to get absorbed into Apple?

I can easily see them being a massive acqui-hire, as they've solved the problems Apple, Google, and Microsoft (lexicographical order) have been trying to solve for years, and I mean the technical problems and also the marketing problems.

I don't pay for dropbox. I love it, but I could replace the utility it affords me with a couple of shell scripts and an S3 instance in a heartbeat.