Dropbox is actually a great example of why this isn't likely to happen. Deeper pocketed competition with tons of cloud storage and the ability to build easy upload workflows (including directly into software with massive install base) exists, and showed an active interest in competing with them. Still doing OK

Office's moat is much bigger (and its competition already free). "New vibe coded features every week" isn't an obvious reason for Office users to switch away from the platform their financial models and all their clients rely on to a new upstart software suite