Their explanation would be good in static world - we give non-english speakers opportunity to be a part of global SO. But I'm afraid that in the future it will

Their explanation would be good in static world - we give non-english speakers opportunity to be a part of global SO. But I'm afraid that in the future it will hurt main SO, since core community of each language will move to its own *.SO, leaving english section for native-only speakers. Of course, maybe that won't be the case and I hope they will watch for negative effects. English language as an intermediate for all programmers is a bliss. Imagine how it would be nice if all people had one language and there were no communication barriers (damn Babylonians :) It's not possible in common case, but with programming we almost have it.