big exchanges will never accept the hacker's wallets
so A lot of you see it as 500 million XEM getting dumped but all I can see here is 1 person holding 500 milion xem for eternity

That's the way I see it as well, they're holding 500 million XEM and cannot exchange/sell them. I would suggest that person approaches coincheck and makes a deal with them to return the funds for a monetary sum. It would be in the interests of both parties.