I think a flaw in your argument is that you are speculating about the future of bitcoin, but applying the current day bitcoin wealth distribution. As if as we go from here to sole reserve currency, it won't change dramatically.
First attempt to prove that after bitcoins grow to the point of being sole reserve currency half the bitcoins ever created will still be in their current owners hands. I think it's possible that there would be enough distribution of coins along the path that at the end of the road the concentration aren't in higher ratios than with our current system.
I think that is being extremely optimistic, but even if your scenario were to prove true-- nothing in the world would change at all, so what would the point of the currency be? Maybe I'm asking too much, but in other words-- what would be so revolutionary about it?