Well, 6.1.6 only applied to one of the iPhone models directly as at the time the other models could support iOS 7 that was already released, so the same fix was made in 7.0.6 for those. Had iOS 7 still been in beta stages (after it was already announced but before it was released) that kind of a release would have been for all those phones that were still on iOS 6.
So, we are basically saying the same thing, that there can very well be a release of iOS 7 even once iOS 8 is announced if there's something there to justify it (some security and/or other major issue).
However, that aside, there are still at least a couple of months before iOS 8 would likely be announced, during which there can easily be one or even more iOS 7 updates too, especially given the potential issue that go the thread going.