Meanwhile, the whole sync mechanism of Dropbox doesn't really matter for a "filesystem of the web", because changes can just occur directly in the remote filesy

Meanwhile, the whole sync mechanism of Dropbox doesn't really matter for a "filesystem of the web", because changes can just occur directly in the remote filesystem rather than locally with syncing Excel can't make changes directly to the remote filesystem. That's the novelty of this scheme. It isn't yet another cloud database, it's a way to share local files with cloud apps. I have mixed feelings about this. It could serve to bring data out of the silos, and back under user control. That would be an epic win. But it's not federated. And I anticipate problems with access control, which needs to be per app, per file, and separate read/write. Aside: I recently had a nasty scare when a shitty iOS password manager deleted my Keepass database from my Dropbox. If hadn't found a copy in the Dropbox cache on my laptop, I would have been in a world of shit.