The next generation of Laptops have just been released but they are still running the G4.
It is unlikely that we will see a G5 laptop in the near future. they are still working on the heat issue.
I'm guess the next major change in laptop configuration will be the release of the Intel powered ones, sometime in 2006/7
Your KVM switch idea will work, just get one without software and you should have no problem.

If you need a laptop now, go for it

P