It wasn't so much that PySide was dropped, as the whole of Qt was dropped (by Nokia). PySide development was funded by Nokia, which owned Qt, and done mostly in a Nokia R&D institute in Brazil (INdT). Nokia sold Qt to Digia, and Microsoft bought Nokia, so there was no connection anymore between Qt and the people who developed PySide, and so it stalled.

Digia later spun off The Qt Company, which develops Qt and is now developing PySide2, so this is actually the first time the same organisation has developed both Qt and Python bindings for it.

For many purposes (including mine), PyQt is very expensive, so I'm really hoping PySide2 goes somewhere.