Doug,
One of the big auction houses had one of the handful of Magna Chartas up for auction within the last year or two. Not everything of historical interest in in the hands of museums or governments.
Ron,
I'm sure they will get the majority of it back. Ebay has all kinds of records that list all the stuff that happens. There may be one or two instances where something may have been lost/destroyed, or someone just says it is.
Steve