Those are the musings of just one man. Granted, Walker does seem to be making an effort to stay nationally relevant, but I think it's almost impossible right now to say whether he'll be in a viable presidential run postion in four years. If he gets through another batch of reforms such as he described in this speech, they kick in, Wisconsin soars and he's re-electec by landslide in 2014, then yes, he'd certainly be in the Ryan/Rubio/Jindal mix.
And while it may seem small consolation now, as we face another four years of President Obama, imagine a primary with those four men. Well, let me put that another way; imagine the intellectual level at which that primary debate could take place, if they four don't make the Thompson/Hovde/Neumann mistake of Mutual Assured Destruction.