Even if you choose Joomla 3 component still only Legacy classes will be used. It would be great if native Joomla 3.0 paradigma will be supported in future versions.
I believe the Joomla 3.5 roadmap discussion includes the final MVC refactoring of the CMS as being on the plan.
That being said, there is no reason to wait for the core CMS extensions to do MVC refactoring as the Base classes already exist in the CMS for the new MVC. A good tutorial for seeing a component built on the new base classes is the Lendr component tutorial. lendr.websparkinc.com/