In Northern Europe they are already there. For the past few years my country (-25c during winter) has required all new houses to be heated by a green energy source - which rules out natural gas.
The price of a heat pump vs a gas boiler + gas network connection are basically the same, and running costs (for prices here) the heat pump is cheaper, especially if you combine it with solar PV.
However heat pumps only really work well when the house is already efficient. New homes here are wrapped with 30cm of foam insulation - you don't need much more than a hair dryer to heat them. If you have radiators that need 70c water flowing through them to barely reach a 18c room temperature, a heat pump won't work - which excludes 90% of UK houses.
The price of a heat pump vs a gas boiler + gas network connection are basically the same, and running costs (for prices here) the heat pump is cheaper, especially if you combine it with solar PV.
However heat pumps only really work well when the house is already efficient. New homes here are wrapped with 30cm of foam insulation - you don't need much more than a hair dryer to heat them. If you have radiators that need 70c water flowing through them to barely reach a 18c room temperature, a heat pump won't work - which excludes 90% of UK houses.