Well... I have a watchface on the old store. It is non functional because external APIs changed. I just recently decided to update it, and there is now a much improved version in my github account.
I asked Rebble weeks (!!) ago to give me back access to my own account and binaries on their store and to this day, I heard nothing from them. Nada.
If Core start a new store, I will immediately put the new, much improved version of my old watch face on their store. Rebble can keep the old, non-functional one in their archive if they want.