I don't see why an application could not ship full Qt runtime in a pinch. Qt4 & qt5 can exist side by side so the binary compatibility should not be an issue. I'm not 100% familiar with Harmattan security/permission issues though, especially as it relates to multimediakit. Btw. I wonder what is the "Community" you refer to? Is there somewhere a village where the mayor has the keys to N9 repos so there could be dependency to Qt5 in a .dep and it would automatically install them? The trac link you posted looks very interesting. Thanks!