OK, I called them up. According to the fine lady on the phone, Q3131 had been replaced with Q3131A. While they currently have none in inventory, they ARE still making it and it is in the 2006 price list. Alot of it is going to Iraq. She says it's in very high demand, but they ARE still manufacturing it, and to the best of her knowledge there are no plans to stop this - even for civilian use.
Your best bet is to buy from a distributor who hasn't run out yet. More will come.
See? One phone call clears everything up.
ETA: To clarify, I called Winchester, not a distributor.