And for the record, after asking around, the real reason Jolla is stuck with ancient Qt is because the QtWayland compositor module "graduated" as a non-essential Qt addon and thus changed license from a mixture of BSD+LGPL to GPL only. Only essential Qt components (like the client parts of the Wayland module) remain as LGPL.

Since Silica is apparently still not fully open, this puts them in a problem as the compositor process is linking Silica and Qt Wayland Compositor together. (Plus a lot of porting to do, anyway).

The issue is not related to GPLv3 at all. In fact Jolla is already shipping some GPLv3 software in the device images (at least for the original Jolla). E.g. I've just checked and GPLv3 readline is used, for example. So much for the GPLv3 FUD...