I regularly take my PVR along to a holiday home where we have no satellite dish, and can still access the recorded content. So I think if you were to disconnect the cables before you cancelled you'd still be able to watch the recorded content, although you obviously wouldn't be able to use the PVR for viewing your current bouquet then.
Any idea how long ago the oldest recording was made ? would point in the direction that there is no timeout/refresh checking for an active subscription.