Well, I was under the impression that AmigaOS needed some sort of activation key which was stored in the AmigaOne ROM. Either way, PearPC isn't going to entice people to use AmigaOS or MorphOS on a Wintel box. At present, the performance on a high end Wintel would be comparable to a 60 MHz 601 (or a PowerMac 6100) -- according to the to the PearPC website. The only real threat would be from something like Mac-on-Linux, which would only run on a PowerPC anyhow.
So ask yourself two questions on the piracy front: is piracy of legacy Amiga ROMs and OSes a problem? I would venture that the answer is no, and I say that for a couple of reasons: there is a vocal oppositions against piracy in the Amiga community. This is unlike other platforms which are comparably obsolete where people say piracy is bad, wink, wink. It is also unlike slightly more obsolete platforms where piracy is the norm. You also have a vendor who was good enough, or desparate enough, to license their ROMs and OSes for use in emulation. Would something like PearPC or MOL change this. It certainly wouldn't change the former, and selling their OS independent of hardware would be a continuation of the latter.
Would emulation or virtual machines be a burdern to the vendors or AmigaOS or MorphOS? Any answer to that question would be pure spectulation, but my speculative answer would be yes. My reasoning is simple: the people who are genuinely interested in using these operating systems are probably willing to pay the price for the hardware, and there are margins to be made off of hardware.
Would you loose potential, genuinely interested users? Sure you would! I'll use myself as an example: I'm tired of the status quo in operating systems. They are slow and bloated, which doesn't fit my philosophy. Would I be willing to dump serious money into an alternative? I already do (I already run Apple hardware). Am I willing to do so sight unseen? Absolutely not. It looks like an AmigaOne G4 would cost over $1000 Canadian. If I don't like the OS, I would loose a considerable amount of money. On the other hand, if it was a $200 OS I would be much more likely to buy it sight unseen. I am desparate for something better than what I have after all. Once I know that I like it, and am confident that I'll use it for a couple of years, maybe then I'll buy the hardware. (Which I would consider to be a step backwards in portability and power consumption in the first place.) Of course, a few odd ball users such as myself may not make the OS only route a smart option. (I don't even believe that it would be a smart route for Apple.)