[QuarterReptile]

>Overall that seems like a reduction in total emissions, since you're using less natural gas overall to heat the same amount.

This just isn't the problem at all; it's obviously a problem, but not the constraint here. Fossil fuels let you store energy in a distributed fashion (e.g. cutting and stacking firewood for the winter), which is way better for handling peaks.

If too many people get burnt by oversubscribed grids in the winter, I would expect that the middle- and upper-class response will be propane auxiliary heating systems.

[Kirby64]

Natural gas doesn't really allow a consumer to store energy. Nobody has a tank to store natural gas next to their house. Yes, you can do that with propane... but it also now requires you to have a heating system compatible with propane (it's just a nozzle change for most NG units... but still, that's way beyond the capability of most homeowners to do).

The only thing that using natural gas to burn for a furnace (vs. using it for a heat pump) gets you, is that you need more natural gas generation plants and the infrastructure to handle the additional power on the system. On the other side of the coin, you have all the natural gas infrastructure to each house premise to maintain... which can leak, have issues, etc etc etc.