Does it not emulate a terminal and therefore qualify for number 7? It seems that when you start up one of the snapshots, it provides a persistent terminal session, in the browser. And isn't the browser itself a terminal for controlling a remote computer?
Certainly one could just create a tar ball of a terminal when logged into it and download it, so the data is exportable, right? Terminal could make that more convenient for sure, and probably will do so.
Software updates could be done the same way it always is: Run a script in a terminal that updates all packages. One could snapshot first, and verify that the updates do not break things.
After a few years, it's a safe bet that updating will break something. At that point, assuming you even notice the brokenness, you've got to either fix it manually (without necessarily knowing how to distinguish a working system from a somewhat-broken one or where to start debugging) or give up. I'd expect most users to give up.
