AmigaOS development is going on for Intel hardware, it's called Aros. For Hyperion to port their AmigaOS4 to Intel hardware would take years, and by the time the port is finally finished Aros would have evolved years beyond. It would make very little sense for them to waste their time when it has taken them this long just to get a decent, stable PPC OS and finally some powerful (by Amiga standards) PPC hardware designed exclusively for it that offers an interesting new hardware design compared to previous PPC Amiga boards.
Hyperion just don't have the money or the man-power to make a competitive OS for the Intel market, so sticking with the PPC niche market is the best route for them at the moment. Remember PPC isn't a dead-end, just because there are no major desktop computers using them anymore (Apple). The Power architecture is in use in the Nintendo Wii, Sony Playstation 3 and Microsoft Xbox 360.
If you want an Amiga with the most powerful CPU you can buy and cheap hardware, give Aros a try. If you've got the money to spend on something a little different and more efficient, give the X1000 and AmigaOS4 a go.
Of course if you want to try the most advanced Amiga Operating System of them all, you only need to pick up a G4 MacMini second hand and download the MorphOS 2.4 ISO, burn, boot it up and install it. If you like it, pay the registration fee to unlock unlimited usage.