My interpretation is that I could switch to LGPL Qt for client software and keep my source code if I dynamically link to Qt.
I may be too strident as a commercial developer in my anti-LGPL 3 rhetoric, but my cloud-apps have been avoiding it assiduously. Client side, I should look for this kind of flexibility.
Even the GPL should not be a problem for you in the cloud, since you're not distributing the software, just provide a network interface to it. And the LGPL is even more forgiving. This web service use case is the reason for the AGPL, which does prescribe that even web services should open their code, should they use AGPL dependencies.
