Seems to me that the correct strategy for Dropbox would have been to be super focused on the core product and on not hiring in too many people/taking in too much capital. That would of course have introduced a market cap, but if 1% of everyone had ended up on a reasonably priced personal plan it would have been a roomy cap.
As it was, Dropbox has grown into yet-another ms-office-in-the-sky and there is no way they will make it against their competitors who can burn the cash, and who are slowly catching up on sync technology.
This is really a shame too: Dropbox is just the gold standard for sync. Before Dropbox I was using unison[0] and tried every other sync product, but nothing came close. TBH I am still using Dropbox every day, getting around the device limit by sharing stuff with multiple free accounts...