I've checked out the updated PyOtherSide and can confirm that it looks very very well & all the examples work just fine (using Python 3.3 and Qt 5.1.2 on a PC). So I'll say PyOtherSide is most probably the future for Python & Qt5.

Basically the only thing missing in PyOtherSide for my use cases at the moment is image loading from Python data objects. So I've written a detailed feature request and posted it at the Github issue tracker.
Looks like THP likes it, so it will hopefully soon be added to PyOtherSide.

Regarding my current development plans for Python & Qt5, I'm going to start working a PyOtherSide based Qt5 GUIs for modRana and Mieru, using the QtQuick Controls components. Like this the resulting GUIs should run just fine on Sailfish, Android, Ubuntu-Touch, Tizen, desktop Linux and once it gets Qt5 also on BB10.

Fremantle, Harmattan and other platforms (there are still people using up-to-date modRana on the Neo FreeRunner, seriously! ) will be covered by the existing GTK and Qt4 GUIs (I'm not dropping those). Of course the Qt5 GUI will also run there, provided at least Qt5.1 (QtQuick Controls were added in Qt5.1) is available.