We won't see a new OS X naming scheme until there's a major, generational shift in what OS X is, for the same reason that the next phone, as you say, won't be c

We won't see a new OS X naming scheme until there's a major, generational shift in what OS X is, for the same reason that the next phone, as you say, won't be called the iPhone 5. The names wouldn't quite make sense, and a simple and easy to understand lineup of products with simple and easy to understand names are fundamental to Apple's presentation. They won't screw that up.