I remain very unconvinced by measures like this on two levels:<p>First, Why not do it now? Or in 12months? Making promises that rely on future people to fulfil them single handed is the same as doing nothing, just with better PR.<p>Second, I'm really unconvinced electricity can reasonably fulfil the same jobs currently done by gas. I don't think you can run a boiler with the same power. If you do somehow build such a boiler affordably you'll have big issues surge capacity and supply levels.
Unfortunately, these long timelines slip or the project is abandoned when a new administration comes in. If the next mayor continues the plan, it might have some legs.