[Gen.Blather]

My dad came from Sweden when he was five. He spoke no Swedish in the United States. When he called Sweden once a year or so, he hand little to no trouble making himself understood. He died at 95 still able to speak Swedish.

[Vigilanteman]

Correct. I spent nearly 15 years in Japan, including some time with total immersion in the language and culture. There are a few of the newer expressions and idioms which might throw you off balance and you might even be a little halting at times, but you do not lose the ability to speak.

My youngest daughter was born and raised in Japan, went to Japanese schools, had only Japanese friends, the whole nine yards. She spoke a little English at home, mostly to her mother.

Same thing even then. She used her math time (where she was far advanced of her classmates) for time with a computer with the Rosetta Stone software. She was up to her grade level by her second year and graduated with honors three years later.