The gas thing is a bigger issue IMO. The 'standard' HWH now as I get it is a low-eff, atmospherically vented gas-fired tank with a thin aluminum vent stack. The 'building performance' crowd has hated these units for a long time...besides the low efficiency, the vent stack is usually open to the space intentionally, pulling huge amounts of conditioned air from the building 24/7 (and through the tank stack increasing tank losses). AND, as folks airseal and build tighter houses these things start working less well, backdrafting, and becoming major CO hazards.
And in 10 years they will all be gone, replaced with units that are sealed combustion. Welcome to the 21st century.
Of course, retrofit will not only mean a more expensive unit, but now also require replacing the venting. Of course, if they are power vented, the existing Alum chimney stack can be abandoned and a vent run sideways out the wall, but it will still mean an expensive and complex replacement, when folks are usually in a hurry, no hot water. There will be much cursing of the EPA I think. And a few 'non-code' venting solutions, like attaching the outlet to the Al stack. And some folks just cheaping out with an electric tank instead.