I think so too. MacRuby is perfect for Apple, as they control its implementation, and the syntax is far more approachable than Objective-C is. Also, no performance penalty when compiled, unless I'm mistaking.
Thinking on it, I'd only be slightly surprised (and extremely delighted) if native/official (as opposed to experimental) MacRuby support for Xcode and the new Mac App Store was announced at the next WWDC.
The engineers might now work on MacRuby, which is rumored to be the up-and-coming second language on OS X real soon now.