[TheSwede75]

Not for long I would bet.

S3 is a great service don't get me wrong. But for relatively low transaction data like backup and sync not only is the pricing high but Dropbox also have a vested interest that as they grow they do not depend on a 3rd party for what is no doubt the largest single cost of providing their service.

[mryall]

I guess it depends on whether Dropbox think they could implement the same storage service cheaper themselves. S3 actually offers a lot. They have at least four nines availability (and I think you can pay for more), a ridiculously high durability figure, plus geographic distribution and replication.

Developing that for yourself would be very expensive, I imagine. I'd actually be quite surprised if Dropbox went through the hassle of setting this all up. It would have to be a significant difference in cost to justify the effort.