[itimpi]

I believe that something like this may be on the roadmap - but if so it is a LONG way off. I must admit that in practise I do not see how from a technical perspective it could operate as you describe as there is no standard for accessing cloud based files.

What is much more likely to happen (and IS on the roadmap) is for the Calibre database and library to be held on a remote database server and shareable between multiple Calibre front-ends. Even this requires fundamental internal changes so is not happening quickly.