From the definition of Mises, if we think and speak multiple languages then we could claim ourselves from the "nationality". I think the author puts a bit too much emphasis on the language.
Last year I have visited the museum of Japanese immigration in Saõ Paulo, and it definitely seems that when the Brazilian portuguese gave the order to forbid schools in Japanese language (in the thirties I think, or maybe during the war), some identity may have been lost.

But as far as I can tell, even though language skills in present days are not good, or makeup, culture, etc are different, they don't totally identify as Brazilian but also as Japanese. One old couple I visited had in their apartment a picture of... the Emperor Hirohito. They were watching Japanese tv, but could not read subtitles since their reading skills are bad.

I think other factors like leaving our country of origin, not paying taxes there, having no social relations, different skin color, traveling are important factors as well.
After more than 10 years not living in the country I am from, I struggle to laugh at political jokes, and I giggle when I hear about "our" motherland.
I digress but if stories of extra-terrestrial beings having sex with humans were real, I wonder if their children would identify somehow as Earthlings without speaking one language on Earth. My guess is yes.