Heat pumps twice as efficient as fossil fuel systems in cold weather, study finds
(www.theguardian.com)
That's a fair argument. Even if every used a tiny bit, there would still be a lot of loss to the atmosphere through leaks/etc of the distribution system.
So yes 100% elimination would be ideal.
But this could be a viable middle step between 100% gas heating -> Supplemental/Heat Pump -> 100% Heat Pump