KF5 Porting question regarding KFileDialog

I'm porting kolourpaint to KF5 and see that KFileDialog is marked deprecated and
QFileDialog should be used instead.
However QFileDialog does not have the same functionalities as KFileDialog,
e.g. the possibility to show a preview widget or
to add another widget to select save options (e.g. Jpeg Quality, etc.)
or even to use the special "kfiledialog:///<keyword>" start url.

So a complete removal of KDE4support lib seems not possible.
Is there anything in the queue for Qt5 integration or shall I stick to
KFileDialog for the time being ?
Or shall I bake my own dialog using KFileWidget ?
What did other apps do ?