It's really more about production than integration. We simply don't have the supply volume or production capacity on hand to rapidly replace existing ICE cars. Things are improving, but overall cost is going to stay high until lithium battery and other costs come down.
Then, you have the issue of rolling out updates to grids. There's a variety of options, all well technically understood, and little movement in many areas. California, for example, ought to have buried a lot of its electrical lines. Construction work during droughts seem like a good way to start a wildfire, as is installing new overhead lines.
