I was at the Washington Utilities and Transportation Commission meeting in Olympia, Washington on the subject of electric vehicle infrastructure last month. None of the utilities represented there expressed any concern about either short term or long term problems caused by electric vehicles. The ramp-up is going to be very slow, permits for charging stations will give them advanced warning on neighborhood clumping, and we'll have decades to build the capacity required as EVs become a significant load on the grid.
The Nissan Leaf and Chevy Volt each pull 3.3 kW maximum. Compare that to a hairdryer that pulls about 2 kW or an air conditioner that pulls 2.5 kW.
People who want to worry about this problem like to note that it takes 8 hours to charge a Leaf, but that exaggerates the load. Driving a mile in an EV uses about 320 Wh, wall-to-wheel. Most Americans drive under 40 miles per day, or about 12.8 kWh, so the average charge will be well below half of the maximum charge. It's analogous to a gas car: just because your tank holds 20 gallons doesn't mean you burn 20 gallons every day.
Unlike air conditioners that add to the peak load, EVs can be charged overnight. All of the EVs coming to the market have timers integrated into the charging controls, so it's trivial to plug in when you get home but not charge until later at night.
Building out the required long-term infrastructure will allow us to keep hundreds of billions of dollars per year in our local economies instead of sending those dollars overseas.