Surprising, but good news. When Swift was originally announced, I suggested on HN that if they didn't open source it, long term, it would go "the way of Flash" -- eventually, developers would abandon it in favor of more open platform technologies.
That's a completely apples-to-oranges comparison. Open-source or not, Swift will eventually supplant Objective C for most purposes on Apple's platforms.
https://news.ycombinator.com/item?id=7851583