Don't panic. I think everything's going to be OK.
We're going to have to move a lot of code to yet another platform. But it'll be much less work than Tinderbox for Windows -- and a lot of the Tinderbox for Windows project infrastructure will help. We'll still have to cope with two frameworks, but it shouldn't be too terrible.
There are a lot of developers in the Metrowerks orbit, and the Apple explanations perhaps understate the trouble we're going to have. But I think it's going to be fine.