You still need gas for heat and for hot water. NYC is cold, heat pump versions of those work, but not very well (especially not well for hot water).
And for apartment centralized heat and hot water? That would be really hard - these units are much later than the centralized ones they replace.
The amount of electricity it would take to do this though.... I hope they plan for this to take decades, because that's what it would take for them to upgrade their wires.