I doubt people here can give realistic estimates as to how quickly we can ramp up the production of e.g. heat pumps, since a lot depends on how much we're willing to pay for it. There are many areas where we have the technology to electrify, we just don't do it because at current fuel prices pay back times for electrification are too long. There are also simple things like better insulation for buildings that can dramatically reduce fuel demands.

The US produces much more natural gas than it consumes, so changes like this don't really make sense.

Europe started implementing these initiatives a couple of decades ago, it makes sense there as they are a net importer, with residential prices around 3x higher than the US. In my country a newly built house (very low energy demand) is often cheaper to heat with a heat pump than natural gas, especially if combined with solar PV - but that's still more expensive than a home in the US.

The most impactful usages are transportation, as everywhere basically everything is transported by road, and renewable electricity generation, so fossil fuels can be used elsewhere (residential, industrial, etc).