so you're saying that there are a number of formerly rich families at the time who have not made it to the present with wealth intact? I guess that seems reasonable, but don't have any data yet. On the other hand there should still be some wealth today that was not among the wealthiest then?

(of course I wonder how much of that maintaining wealth was - instead of gold, art, and land - strategic marriage)

Certainly there are a good number of formerly rich, now poor or extinct families. It's practically a cliché of nobility.

yes, it seems likely, even 'certain' but as I understand it also seems not to have been verified using data in this case? I like my certainties verified.