There's just no easy way forward out of the swamps of C-level memory management that doesn't break the world in some way. Even turning on GC (as we have under OS X) isn't a panacea: there are plenty of Core Foundation kinds of calls that don't participate automatically in GC (you have to manually connect each such allocation to GC). And with "unmanaged" pointers at the C/Obj-C/C++ level, you'll always have to step gingerly around GC.
And he's right to think ahead 5-10 years and realize that we're probably not going to be doing manual memory management then.
So what's the way over the chasm? I don't think anyone really knows, even at Apple.
Perhaps (pure speculation) the MacRuby efforts are part of a back-up plan to see if a ("managed" by definition) dynamic language could help bridge the gap without breaking the world. The MacRuby compiler claims performance on a par with Obj-C or better (using LLVM).
It'll be interesting to see how this plays out.