It seems we're headed that way, anyway. Check out this article about a guy who was taken out by security after being overheard speaking Tamil on his cellphone at the Seattle airport. And what about the two Orthodox Jews who caused a flight to be diverted by praying in Hebrew (link). And language-in-airport issues aren't just in the U.S. Two guys were kicked off a flight from Malaga to England when they were overheard speaking what fellow passengers took to be Arabic (link).
Next time I fly, I'll just keep my mouth shut.