I've looked to make a dummy booking and SQ still loaded in mid-February 2021 with A380 on JFK-FRA. I do hope it stays! If they changed it's departure on the return (eg, leave FRA later) it could garner much more attention for Euro travelers (and the nonstop out of SIN would still give people a morning arrival into NYC). AC also wouldn't then sit for 12 hours in JFK.