I had strong feeling that wasn't the last we've seen of that sort of non-Gallifreyian TARDIS and it bore a lot of asthetical similarities to the Pandorica, the feeling of vindication is wonderful. But I doubt it's the same counterfeit TARDIS from last time, the Silence's more sinister, somewhat cruder TARDISes might be around in huge numbers if there's already a huge army of the Silence lurking beneath the surface of our planet, with their timeships presumably used as power/control hubs for their endless underground warrens and tunnels.
A Silent drone is a cross between a Roswell Grey and the
Slender Man, their mind wiping ability is an unnerving and practical trait.
I'm guessing the Silence are future evil offshoots or direct descendents of the Ood civilization that we saw from "The End of Time", where the 10th Doctor was remarking with some concern on how fast and far the Ood were advancing as a species, with sprawling cities and immense psychic powers already developed within a relatively short space of time. The Silence do have more similarities than differences to the original Ood, with their bulbous skulls, killing through electricity, and psychic powers...