This is similar to what I hoped websql had eventually grown into. sqlite in the browser, but let me sync it up and down with a server. Every user gets their own database, the first time to the app they "install" the control and system data, then their data, then writes are synced to the server. If it became standard, it could be super easy - conflict resolution notwithstanding.
You can make webapps using exactly this approach, with json in localstorage as the client db, and occasiona, asynchronous, writes to the server. I'm now building a simple webapp exactly like this, and the server db is sqlite. So far it works perfectly fine.
In my experience the size limitations of localstorage keeps this from really being viable. And I just really like SQL. But your point is well taken, it is possible to do it today. My hope back then is that there would be libraries over it that would have made it easy and commonplace.
