But that replacement doesn't need to happen quickly, cars won't get replaced sooner well... than the cars are replaced, which is, about once in 15 years. Even if market share of electric cars in dealerships is 100%. So grid requirements will evolve slowly through about 2050, not overnight - which is hardly faster than its normal renewal rate.
In my neighborhood there has been no electrical grid upgrade (other than repairs) since the 1960s (when the subdivision was built). I think your 15 year timeline for normal grid renewal is wildly optimistic at least for most established suburban areas.
Also few people keep their cars for 15 years. I think 5-7 years is much more normal (though perhaps you meant the total life of the car, from original owner to the last).
Personally, I keep cars until they're no longer reliable/economical but the average length of ownership is presumably lower and brought down by people who get a new car after a 3 year lease. Although the overall length of ownership has been increasing because of improved quality.
Given the trend (in Germany) to crack down on ICE cars, you're looking at a way shorter timeframe. Once the first court OKs ICE bans, stuff is going to get nasty.
