I can't see how Dropbox wouldn't end up getting crushed in this fight. Just recently, they reclaimed all the promo/referral/college storage I had, and shrunk my space from 40GB to 15GB. Pay up $10 per month or lose all your data.
I shopped around, and got a $2 per month from Google Drive. The product is pretty much on parity with Dropbox on the Mac, and works exactly the same way. Yes, I'll take that 80% discount, thank you.