Why do I think Oswin getting hit with a memory wipe when she leaves the Doc is going to loop back around to set her up for Asylum of the Daleks?
I doubt the Doctor's interest in memory wipes here will continue to be a part of his character. I think, as I said, it's meant to show that he's gone to a darker place, a place that Clara will help bring him out of.
And this isn't Oswin Oswald, it's Clara Oswin. We don't yet know how the two characters are connected.