I am not too sure about that.

1) Yes in an insane example where everyone runs out and replaces their car with an electric car that might be true. But assuming that it will happen is a bit nuts since cars are a big ticket item and so even if we assumed the government passed a law tomorrow on a whim that only allowed new cars being sold to be electric it would still take well over a decade for everyone to be driving an electric car.

2) electric cars don't use that much electricity, that is why here you have chargers that only cost 2.50 per use (and you can fill up for that). For example if we go on Tesla's site if you have the dual charger that does 240V 80A 1h of charge is 20 kW and that translates to roughly 58 Miles of driving

3) you are looking at it too simply. The electrical grid is not like your shop where you say "we need more employees or we have to not take some jobs" if demand grows all of a sudden by a lot because there is only so much any employee can do. The electrical grid is variable and is build like roadways (except a lot better). You have that large highway going into the city because it is needed during rush hour and not because it is needed 24/7 so off peak hours it can be relatively empty. The equivalent of high traffic on the roads during peak hours when it comes to electricity would be brown outs and possibly blackouts but they don't happen often, because at peak times when the power plants are running full steam they produce enough but since electricity can't really be stored (and I know the irony of the statement since cars and their battery are essentially storing electricity to be used when driving) that means that production is directly connected to usage and so capacity is turned down. If we assume somewhat smart car meters in peoples home you could have a lot of people charging their car with no need to increase the capacity of electrical consumption. Let me go with a simple example you have 25 people that are watching their TVs that use 800 Watts/hour at 8PM, if none of them are watching TV at 2AM and someone is charging his car at that time the amount of electricity needed is the same and the car replaces those 25 TVs and Tvs are not even the big hogs in the home, I used them as example since it deals with a subject that we are familiar with and it is easy to find 25 households watching TV at the same time (let's say 8PM). But if we go with a 2KWh clothes dryer (low end) one car charging at night would be the same as 10 people using their dryer at the same time during the day and if we go with a 5kWh dryer (one at the higher end) that would mean we need 4 people using that dryer at the same time to match the electricity needed for that car charging at night when they are not using the dryer.