I know that this might seem to be controversial, but I think there are a fair few 747s that have been set aside for preservation, but only a few of them seem to me to have secure futures. Most of them seem to be outside and those which are in Europe, at least, seem to be at risk of much the same fate as N747PA.
Preserved aeroplanes need to be indoors, but the cost of having a 747 indoors seems to me to be prohibitive. Although N747PA has gone, it won’t be the last.
Regards