It's possible I know many of mine left as I let the catch bin fall over, if I was a bsf that didn't want to die over winter after a mishap in the greenhouse. Id go over to my neighbors grow up where it's warm and damp all winter and they leave garbage everywhere, yeah you could establish cold tolerance and move out. But it would probably take 20 years of evolution before they would be commonly identified. But no in all my compost heaps and barrels of experimental lazy bokashi trials I've never seen one return. It would almost be like how locust plagues usually come from just a few "ideal condition" hatching grounds the bsf of a region through it's warm season could be spreading serially all summer trying to find a new ideal condition. But really be coming from the same ol refuse leak at some factory where there's a micro climate that suit's them year after year. I'm sure if I had a decent 50,000 sq ft polytunnel they would stay year round and try migrating out every season, granted it being heated by compost and rocket mass aquaponics in the winter might help.