I have mixed feelings about this.
On the one hand: more Girls Und Panzer is good to see. I’m also hoping that whatever local disc release occurs will include the OAVs.
On the other hand: The strength of Girls Und Panzer was largely in the episodic format, with character development occurring naturally over several episodes. For example consider the transformation of the Rabbits (the freshmen) from scared to scary over the length of the series.
This raises the question of how well the series will adapt to movie length, and I do have my doubts.