Sure but it's a distant pivot. It's almost starting over except they have a company with revenue. Adobe also has that and each new product attempt fails or wins independent of Photoshop's success. And Adobe and MS products are more related to each other than file backup and editing.
Dropbox the product is a good revenue stream and could spark another Microsoft/Adobe style multiproduct software company.
Is that Paul Graham meant by start to chip at the big vision with a beachhead though? Because then any product idea has that potential, as long as it starts the first company. Seemed like he was advocating for a more direct path, hacker search to more general search, basecamp to email, etc. Starting companies is hard anyway, start with a clear path to something big.