I buy and resell a lot of 40s and 9s because I have no interest in them. You do see an influx of some calibers at different times. I see a lot of police in trades and like to buy them in bulk to resell as they often have a lot of holster ware but were fired less then 500 times. Clean em up nice and they sell pretty fast.
I still think of the 40 as a gimmick round and doubt that it last like the 9s and 45s. I don't think this is a sky is falling time for 40s just the ebb and flow.