I understood that part. However, there is no guarantee that Germany will still accept dual citizenship in 50 years. There is no guarantee that Germany will not

I understood that part. However, there is no guarantee that Germany will still accept dual citizenship in 50 years. There is no guarantee that Germany will not (again) become a dictatorship where people are interned in camps if the ruling class finds it politically useful. There is no guarantee that Germany will even allow you to leave the country in 50 years, even if you have dual citizenship. This is all seems improbable, of course, even ridiculous. But I don't think anyone in Germany could've seriously imagined the situation of 1939-45 30 years earlier.