O365 still gives you desktop versions of the Office software. It does makes me a little worried, but I'm hoping Microsoft isn't suicidal and won't pull the plug on desktop software, leaving us only with the half-featured web versions.
Flow is interesting, but AFAIR it requires extra clicking in the administrative interface to get running, so it might not work for shadow IT as well as Access does.
I am hopeful that between MS's financial commitment to the suite, improved JS performance in the browsers, and a set of practices coming around, it will reach parity in the next few years. I run Linux and while I miss features, I can do my job in an O365 org rather than having to have a mac or run a windows client for office suite.
On the one hand, I'd like it too. I use Linux as a daily driver - but I recently replaced my sidearm machine, and I keep it on Windows, so that I have a computer on which I can run desktop Office.
On the other hand, I'm convinced that once Office on-line reaches feature parity with the desktop, they'll quickly drop files, and turn Office into just another SaaS that holds my data for ransom. I don't want that.
Flow is interesting, but AFAIR it requires extra clicking in the administrative interface to get running, so it might not work for shadow IT as well as Access does.