I fully expect that owners of large caches of bitcoins will sell them privately and discretely to various investors that wish to not use financial exchanges like Dwolla, Mt Gox, and Tradehill.
that's been happening for a while now. remember bruce wagner's post a couple of months ago, on behalf of a friend who would only sell face-to-face in new york, and had a metric crapton of Bitcoin?
the OPs 10-50 people with 50k+ BTC has been steadily dwindling.
in a year, we'll likely be down to satoshi, vladimir (who was not technically an early adopter), and a couple of others.
the stuff is percolating through the world. homogeneity will be forthcoming...