As of Qt 5.4, it's in maintenance mode, and will be deprecated soon.

Source: http://blog.qt.digia.com/blog/2014/12/10/qt-5-4-released/

Development still was continued in Qt's own tree, but as it was mentioned, as of Qt 5.4 only bugfixes will be done.

Though at some point I plan adding a QtWebEngine (i.e. Blink/Chromium) backend to qutebrowser.