This morning an acquisition news got techies excited about Dropbox buying the iOS app with lots of buzz but few invites, Mailbox. In short, this is a hail mary pass after Google announced that you can now attach large attachments with Google Drive integration in Gmail. Dropbox had to react and they reacted by buying Mailbox App.
After their initial security bungling, Dropbox was putting their house in order to target enterprise market. Dropbox is one of the few cloud storage vendors targeting enterprises from the consumer market. In a way Google Drive is in similar position. With Google Apps gaining traction, the Google Drive integration with Gmail is a blow to Dropbox’s SMB & enterprise plans. My guess is that the Mailbox acquisition is a desperate attempt to change the discussion and position themselves as someone with a plan.
I might be totally wrong with this but I am fairly confident that this is the case. I would love to hear your opinion on this.

I have to disagree with you on this one. Dropbox is definitely a couple of steps ahead of Google Drive on several other fronts, for example the fact that Dropbox can share files with non-Dropbox users. That is just a small example. You can already sync your Dropbox account with desktops, laptops, smartphones and even digital cameras. Email is just the next logical step but not a game changer.