SQ practises auto-cancellation of bookings not confirmed by a certain date (usually one week before the flight itself). Since your flight is about two weeks away, you could wait for the booked seats to be released by next weekend (if any).

I would also recommend that you monitor the number of J seats available on the first flight over the next few days. 3-4 redeemded seats can be tough (even in this economic climate).

And to answer your question, SQ should open up the seats to redemption rather than fly out empty, as I'm sure they earn some money from the fuel surcharges.