Who would want to use OSX on a touch screen. Microsoft is trying that right now and it's not working out so well.
It's working out just fine. They did design the OS to be used by either a touch screen or a mouse. Apple will just have to write OSX for both. Much of the OS is already touch (gesture) friendly given the track pad support.
http://www.zdnet.com/microsoft-more-than-100-million-windows-8-licenses-sold-7000014957/