a few options are on the table really. They could merge with iOS or make some other term like mOS.
Apple could stick with OS X and leave the decimals for fine print which don't actually add up to os x (11.3 etc).
Apple could go with a completely different naming scheme like just calling it Mavericks then when the next version comes out a completely new place without any OS X in front. Maybe Apple Mavericks.
I assume they are going to continue with these new naming iconic places naming conventions because they can hardly do only one especially comparing it with how many animals they used previously.
One thing for sure is, they probably have figured it out 5+ years ago. They planned Lion / Mountain Lion (king of beasts) to be the final animal before switching to Mavericks so they must have planned that ages ago. There are a lot of iconic places in the world.