Gradual Loss of Control
Actually, I'm more worried about 'trivial' things like this than killer robots. Here's a fairly famous paper from 1983: http://www.sciencedirect.com/science/article/pii/0005109883900468
If the next language is genuinely indecipherable and is used to exchange information between power plants, for example, then we need to worry somewhat. I agree that the whole story got blown out of proportion in the non-tech news outlets, but there is a worry there.