If none buy by then, then say you didn't say than.

Apple already has a similar system as part of Mobile Me (formerly .Mac, formerly iTools) but they charge $99/yr for it ($10/mo would mean a higher price AND more customers) and don't do a great job marketing it (and it doesn't work as well on Windows).

Maybe they'd buy DropBox just to get people who know how to market this shit.

I would think Amazon would buy it.

I don't know about your time frame, but I agree that DropBox will be acquired eventually.