I did ask Emirates but they are not willing to say anything, it's about trying to get you to upgrade your seat
see reply below

I'm sorry but we can't confirm if and when certain seats will become available closer to the online check in. We can't know for sure if the flight will be full or not and how passengers would have bought and selected their seats. To have your guaranteed seats, it's better to pay as soon as possible and not wait until the online check-in opens. The seat charges are the same whether you'll pay now or closer to the departure date. Trust this clarifies.