I believe nowadays most of Dropbox's revenue comes from their Dropbox Business customers. Or at the very least they see growth in business customer revenue as much more promising. (from my glancing over their SEC filings)

So while as a personal user you might not see many potentials for AI (though I do), I'm sure there's huge opportunities for their business customers. Also if you look at their current offerings you can see they've branched out substantially from just storing files. Signatures, "DocSend", password vaults, etc.