Seems a bit like setting an anchor for a buyout. I have a feeling a 4 billion offer by Google/MS/Amazon would be accepted very quickly even if it was very little cash/all stock. Maybe my sense is very wrong but it seems like a decent time to get bought out timing wise.
Google or Microsoft won't buy them. They're hedging their bet that this technology will be a commodity soon (Google Drive and SkyDrive). It doesn't really fit in Amazon's universe. They already told Apple to screw (albeit only at 800M). I think that Drew is a True Believer, where he thinks there is tremendous growth potential in this space. And hell, anything's possible. Who would have thought that such a simple idea…
Surely Dropbox must be one of AWS's biggest clients? It may not make sense for Amazon to buy them, but the more money Dropbox makes the more money Amazon make (at least whilst Dropbox are still using S3).