I don't understand this mentality. Growth must be explosively exponential or things are bad, so company must sell out, close shop and go.
So, Google should sell Google Drive, Box shall close down, PCloud must cease to exist, Mega shall sell itself to a three letter agency a-la Crypto AG, Sugarsync shall vanish, etc...
Yet we are here. These are all stable products chugging along.
That’s the bargain Dropbox made when it took VC and then went public. Public markets don’t price a company purely on today’s cash flow, they price the expected stream of future cash flows. If growth stalls and the attempts to create new growth vectors don’t work, the valuation adjusts accordingly, and at some point an acquisition can become the rational outcome.