For heating use only, heat pumps are more expensive than natural gas in my area (MA, with ~$0.25/kWh electricity and $0.85/therm gas supply plus ~$1.13/therm delivery).

I tried to make a heat pump make sense for heating here. I couldn't make it economically pencil out. I hope I'm around and I hope the economics are different in 20 years when it comes time to replace the heat source in my house again.