Sounds to me like doing a combination of the three might work.  

Escrow >> Certain holders may not want to go back to the exchange and therefore escrow and or website could be good method (who would control the website functions)?  

Exchanges >> Burn the coins they have for new ones and credit their client account (do balances at exchanges collect POS?)?  Ones that work with us for cheaper fees great and if we want to get relisted another place we have to pay, seems to depend on them.  I understand their may be fees out of Bittrex.  

Just floating some thoughts here, thank you for your responses.  

Maybe a good idea to set a target time for exchanging via escrow, such as X time on X day with a red herring type of announcement?  Time limit makes sense on most fronts but it would be sad if somebody lost their balance strictly based on a time constraint.  Most people holding OC would likely be tech type and therefore be informed.  Lost coins that haven't staked at all might be ruled to be burned after first round of burning coins?  

Just thinking here everyone, stay warm and thanks for all the hard work.

I don't know the ETH contract method.