I am experimenting with Xcode 6 Beta, and noticed armv7s disappeared from Standard Architectures. I did scan through Xcode 6 release notes, but didn\'t see changes on that.
Please note that this answer was made at very early stage of the quest, has been unchecked for answer when Xcode 6.0 GM came out. This is meant only for tracking, refer to other answers for detailed information.
This appears to be a bug of Xcode 6 Beta, according to this thread on Apple forum. A bug has been opened.