I think that some people are greatly overestimating the possible negative impact that WinUAE + decent PowerPC emulation could have. When, in the history of computing, has the existence of an emulator ever killed off the sales of hardware or an OS? I certainly can't think of any examples.
People will still want to run AmigaOS 4.x on actual hardware. In the meantime, WinUAE could give them a cheaper entry to try it out (only need to buy the OS).
Hans