My thermostat is rarely above 65 and my cats are fine with it. If the temperature outside dips to the negative numbers, I may turn the heat up to 68 or 70.
Nope, that's what my thermostat is set to overnight and during the day when no one but the critters are home. Cats have fur coats for a reason and 60F is hardly cold. Maybe not as warm as us some of us tropical primates would prefer, but not even close to uncomfortable for a cat. Unless you have a hairless cat or a cat with thyroid or similar metabolic disease that is less able to control their own body temperature. Most cats will just curl up under the blankets or in a sunbeam if they feel a little chilly.
cats made it threw the outdoors all year round, i mean they find shelter from the cold winds but 60 inside temps nothing cold to a cat. you can set it lower, they got the nice mink coats to keep em warm and if there really cold they can crawl into bed with you at night.