It's one of my pet peeves of Moff's tenure, way too many unanswered questions, eg, we see Amy's parents... and then they promptly vanish again. Or "Silence will fall" Or the TARDIS exploding. He's too distracted by the next shiny thing.
This is one of the reasons I was glad they didn't film the Brian Coda, because it's great that he gets to find out about them, but what about Amy's parents and Rory's mum? At least Brian would have some idea what's likely happened to them which gives him more closure than they got. For them presumably Amy and Rory just vanished!
I like to hope that Moffat hasn't fogotten about the voice...