That is a consideration, since they are used to heat, but warmer temps should be coming. I would think that next winter, just don't use the heat lamps at all and let them acclimate naturally as the seasons change.
If electricity is available, which it must be if there is a heat lamp, invest in heated buckets or bowls to keep their water from freezing and they'll be fine.
How cold does it get? We don't supply heat to our birds. I figure if the sparrows, bluebirds and cardinals can survive in the wild, my chickrns can, in an enclosed coop as long as they stay dry.
Hi, welcome to BYC! You're going to get as many opinions as people who respond, so the bottom line is, after you read all the suggestions, you're going to do what works best for you.
What I think *I* would do, in your very fortunate shoes, is leave your inherited flock right where it is...