Interesting statistics, as always.
I'm not sure if you know this, but it's unlikely the @null account will ever leave the richlist, since not only tokens paid for promoted posts end there, but also all burned tokens go to null. For more accuracy, you might as well not count @null as a "real" account because it effectively isn't.
From my reply to @frot, down below:
On Hive proper there's an automated mechanism that "sweeps" the burned Hive tokens from the @null account every minute or two so there's never a balance. Layer 2 (Hive-Engine) tokens are not swept so the account effectively holds HUGE balances of every Hive-Engine token ever issued that has burned tokens and continues to burn tokens. That's continue to build if/till the base code is modified.
Regardless, I still have a long ways to go to make the top-50!
=^..^=
It is quite wishful thinking that @null account falls out of the top 50, it has witnessed consistent decline in the position in its ranking and I am sure that few accounts below the @null account can power up the stakes and the account falls below threshold.