Yeah obviously there has to be a catch, it just can't be that easy making Universal Binaries.
I believe there will still be support for PPC but most programs will shift to Intel, I doubt we'll see anymore PPC games for example, they are just easier to port and run on an Intel, many apps will remain binary but I bet we'll see a few Intel only apps, its inevitable.
PPC is still good for some time but it will slowly fade away, my G4 DA tower has lasted quite some time since it was bought and I still use it daily and constantly and will keep it indefinitely just for the Mac OS 9 factor, you know for nostalgia purposes and I'll use the Mac Pro for highend. PPC will live a LONG time but by live I don't mean every app will be available but there will still be several software made for it.