How so? He says "on sunny days the miner and whole heat pump are running fully on solar energy collected on my roof", hard to beat that with gas. I would say that moving more houses to all-electric heating, water heaters, clothes dryers etc. is future proofing - right now, a lot of that energy would be from fossil fuels, but swapping in renewables is easy.

Natural gas heating contributes significantly to climate change, and if you're in an area with significant renewable electric (or if you expect you will eventually over the lifetime of your system), you can lower your carbon footprint by heating with electric heat pumps.

You could run a gas generator to power the miners and all of the waste heat could still heat your home.

Most electric heaters are heat pumps which are significantly more efficient than heating via resistive or mining.

In fact a heat pump's efficiency is about 300%.

Just to be sure, you're not talking of those €20-50 electric heaters right? Because you say "most" and afaik those are pretty much the only ones people have unless they're in some fancy new building or have a fancy AC and paid extra for that option.

GP's referring to HVAC systems you'd find eg in a relatively new (1980s+) single family home in America