The premine is only a couple thousand bucks worth at todays prices anyway. BK has bought tons more since then, so it doesn't really matter. I wouldn't be surprised if he's the biggest holder by far at this point, as he's often announced his purchases publicly.
And also remember all the money he spent to keep the blockchain alive (DigiSheild issue) by renting rigs. So premine is definitely not a big issue like the other 2 gents before me said.
But there is one thing that bothers me ... why are we still talking about transitioning from PoW to PoS. Why can't we just implement dynamic PoS on a new blockchain/coin and simply swap out ?