I suspect cases like this are a tiny minority. You could handle them by falling back to the current way of doing this, ie US servers, and still protect the vast majority of data that's not related to US citizens.
Knowing people in other countries is a tiny minority? Maybe in the US, given its size, but it's pretty widespread and normal in Europe.
I belong to a group that has several connections in countries all around Europe due to frequent traveling to dance events. Most of these people post on Facebook in their own language and attend local events.
Outside of this bubble, things are very different. The majority of people never move from where they are born, speak poor English and never travel.
While the people with international connections are surely a relevant amount, and even adding expats that keep contact with friends and family, it's the group with not international connections that I would define as "widespread" and "normal".
Absolutely yes.
Especially across two continents.
Europeans who have friends from Europe would all be in Europe anyway.
Europe is larger than US btw, it has two times the population.
Russia+Turkey+Germany alone account for 95% of the population of the United States.
I believe, in the context of this proposed ban "Europe" means "the EU", not geographical Europe. So both Russia and Turkey don't count.
Globally, around 1 person in 30 lives outside their country of origin, so knowing people in other countries should be common.
Not most, just some.
1 out of 30 is a bit more than 3% and many of those have family connections, they are not strangers living abroad, they are - for example - Italians living in Canada.
EU citizens whose data should be kept in EU.
With Facebook’s lowering importance and my self getting older, my interaction with non Americans has lowered. If we are talking about the EU only, the amount is minimal.
Thinking about others around me, most don’t have anything significant with EU residents or have one specific set of friendship[s] in the EU.
The question is potentially very difficult, and could only be resolved by constructive engagement with the party making the rules.
Don't forget what happens when people travel.
We do want to make it easier for Facebook for political reasons, though, and it's still not particularly hard: just declare that only the data/conversations involving US citizens can be stored on US servers.
Borders are heavily controlled by USA, why shouldn't other countries to the same?