In the sixties it became popular among urban planners, at least in the American Midwest, to have shopping districts ban cars. It did not prove popular, in fact you could say it led to the rise of shopping malls. Most if not all of these car free plazas were torn out. Is history repeating itself in Europe?
What happens if everyone moves to electric cars and the pollution problem from car exhaust disappears or is greatly abated in the inner city? Does closing the street off still make sense?
You should visit Europe once, you'll see that life here is different.
Specifically regarding Friedrichstraße: It's in the city center, brimming with tourists. 3 major subway lines have stops there. Few cars drive in there as it is, because you have bigger streets nearby that are better connections. If you still want to go with your car, you just park in a parallell side street, there are even parking garages if you don't want to look for a spot.
Having it car free will be lovely for the tourists, cafés and restaurants will put out tables.
The same was done in other city centers like Budapest or Vienna decades ago, and it worked out extremely well for everyone involved.
Making cars electric means they don't spew CO2, which is important so that the planet doesn't become uninhabitable (for us) BUT it doesn't actually stop them polluting.
Rolling at speed means two surfaces are ground together which will produce tiny particles of stuff that get stuck in your lungs. Which causes a statistically detectable increase in breathing problems, thus a small bump in deaths.
Getting rid of motor traffic in city centres mitigates this problem, regardless of whether the cars are ICE or electric. We can't make it go away altogether because rolling fast is very useful - the public transport will be doing it too, but we can significantly reduce it.
Surely that has more to do with all the people with money moving out to the suburbs and favoring shopping locations closer to them more than it does with a few streets being closed off to traffic.
Americans moved to the suburbs and built shopping malls because of two things: the auto industry, and white flight. Mainly, they wanted to get away from all the black people in the city.
Generations of racism have had a huge, huge affect on American society and the design of American cities.
What happens if everyone moves to electric cars and the pollution problem from car exhaust disappears or is greatly abated in the inner city? Does closing the street off still make sense?