It should be run on Macs to begin with.
The problem is not that OS4 is underpowered on SAMs, but the fact that the SAM is disgustingly expensive, and low powered, compared to its main rival, MorphOS.
The sad fact is that OS4 due to this, together with performance penalties and lack of features, it is notably loosing market share. Example: lack of USB 2.0 support and widely known bugs and crashes that are not quickly solved. It is that serious the situation, that AROS/IcAROS which has cheaper hardware and USB 2.0 support is even gaining territory, diminishing OS4 market share.
On the other hand, many classic 68k Amiga users, are reluctant to commit the huge amount of money on OS4, because it still lacks its "wow" factor, i mean OS4 is "just" good, and the hardware is a boring, unoriginal and underpowered PPC embedded design with the Amiga name on it. And of course, it has nothing to do with the original Amiga concept of innovation and/or great engineering.
My 2 cents