Haven't read all the posts so it may be mentioned before. Current PoS implementations use some sort of wallet weight as a way to handle competitions for blocks. Wallet weight is basically the amount of coins in the wallet. So if I have a big wallet with very small coin blocks (i.e. I transfer the coins in thousands of small transactions), I have the chance of staking a lot of new blocks continuously with the full weight of my wallet each time. That's the problem.

I think the way to fix this is to change the wallet weight to the amount of the coins in the current block that's being split to stake, rather than the full weight of all coins in the wallet. That would mean that you need a lot of coins AND big coin blocks in the wallet to perform a potential blockchain rewrite attack.