According to ACL the slots for Saudia have defiantly been handed back.
They have handed back the 4 they do not intend to use. They had applied for 7, (for either daily flights or to have flexibility of which days they wanted to operate).
The 3 slots for Wed, Fri and Sun are still live and their GDS preview is still live.
I personally think they will start in S14, but, everything is still open for a W13/14 start should they want to.