Rumor has it that the next Mac OS X will be named Lynx. Mac OS X 10.9 Lynx, how does that sound?
If you ask me, I suggest they move away from the whole feline moniker pattern. Cats are sneaky bastards, and Apple's really jumped the shark with Snow Leopard and Mountain Lion. They're running out of names!
How about names of bears? Bears are friendly, but defensive when necessary. Bears also have great names. Mac OS XI 11.1 Kodiak (Bear), Mac OS XII 11.2 Brown (Bear), Mac OS XII 11.3 Siberian Brown (Bear), and so on... And bears are cooler than cats.