In his podcast, Siracusa also outlines a possible gradual transition to MacRuby, where MacRuby is more of a bridge at first and gets more and more native implem

In his podcast, Siracusa also outlines a possible gradual transition to MacRuby, where MacRuby is more of a bridge at first and gets more and more native implementations of Cocoa classes as time moves on. In the end, Obj-C would get deprecated and all the cool stuff would be happening in MacRuby. Having worked with Cocoa, Ruby and PyQt, I would really really like to see that! As others have said though, this is a somewhat unlikely future right now.