Untill today there is no nonstop service from the US to SIN and I hardly doubt that anybody will try SIN-JFK nonstop! I also hardly doubt that the B772LR can fly 18hrs with full pax and cargo. A nonstop service between LAX or SFO to SIN would be a great deal!
The A340-500 can fly that long but u have to leave some pax and a lot of cargo!
a family friend in SQ says there will be economy class on the A345.
anyway the following is just my opinion. I think they'll make it kind of a premium economy class and charge a couple of hundred dollars extra than the flights with a stop in north asia. Who wants to sit in a cramped seat for 16 hours???