It's probably best not to think of Dropbox the company as being about the product "Dropbox." It's a huge company and as with all megacorps their goal is to become bigger through whatever means they have at their disposal.

Maybe they'll come up with something of value to bolt onto what they do today, or maybe they'll add a totally different product to their portfolio, or maybe they'll pivot away from their current business entirely, or maybe they'll just waste a bunch of money chasing the current fad.