Being a foreigner still has an edge, you're "different". Once you cross the perfect Japanese threshold you lose it. My Japanese friends tell me that people like
@Dogen make them cringe and feel revolted because of his excellent Japanese and ask me to never even try speak like him. Seriously. I've been here 15 years and have never met a super fluent foreigner who makes good money. The foreigners in good positions (20 M¥ above) and doing interesting stuff are in general not fully fluent. Speak some but don't aim to be Japanese.