“Washington has been banning the extension of natural gas to new neighborhoods”
Is heat-pump heat as cost-effective as natural gas heat in your fairly mild climate (mountains excepted)?
It depends largely on the efficiency of the "heat-pump", how much it costs, if there are subsidies and what electricity rates are vs gas. Up until recently the vast majority of people chose gas if it was available. On our side of the mountains whole house A/C is not necessary very much of the time. Most people choose to get a couple of room air conditioners when it is hot and leave it at that.
Most places in Eastern Washington are a different story. Natural gas is not as available, the price of electricity is less and it gets hot in the summer regularly.
If it was more cost effective to install heat pumps in Western Washington why would the government step in and ban new gas infrastructure? They already have been providing generous financial incentives to encourage the purchase of heat pumps vs a gas furnace. Their actions indicate to me that at the current time a gas furnace is considerably cheaper to purchase use and maintain. Washington is currently planning on jacking up the taxes on natural gas in the next few years to change the equation.