On the QtWebKit front, it appears every distro is resolved to continue providing it.
Regarding QtWebEngine...
Arch Linux enables use_proprietary_codecs
So does
Gentoo via a USE flag -- although Gentoo has not updated Qt to 5.6.0 yet, so I looked at the Qt testing overlays.
On the other hand, it sounds like Debian and Redhat are in a real snit about it.
I cannot find any Debian QtWebEngine package at all, and it doesn't appear
Fedora enables use_proprietary_codecs.
Both seem to object because of licensing crap. It reminds me why I prefer Arch Linux in the first place. Debian and their "Social Contract" are far more interested in making some sort of cleverly inscrutable political statement than having working software.