There's the small matter of getting an x86 license. Which would mean buying Intel or AMD, since it's vanishingly unlikely that Intel will be handing them out any time soon.
Apple could afford to buy Intel, but antitrust considerations would probably prevent that from happening.
Apple could buy AMD, but the Intel/AMD x86 cross license probably terminates in a "change of control" situation. Which might mean a restart of the Intel/AMD lawsuits of years gone by.
There's the small matter of getting an x86 license. Which would mean buying Intel or AMD, since it's vanishingly unlikely that Intel will be handing them out any time soon.