Being able to run Windows is a key competitive advantage for Macs now, and Windows (due to the problems of application support) will likely never run on ARM. Hence, neither will Macs.
x86 has always been predicted to fall behind competing architectures, and it's always kept up--at least for personal computers--because of the large vested interest in keeping all that x86 code running. History is littered with better-architected CPUs that couldn't beat x86. ARM survived because ARM is an embedded processor, and PPC survives as an embedded processor, but Apple's been down the road of trying to shoehorn an embedded processor design into Macs before, and ended up migrating to x86.
x86 has always been predicted to fall behind competing architectures, and it's always kept up--at least for personal computers--because of the large vested interest in keeping all that x86 code running. History is littered with better-architected CPUs that couldn't beat x86. ARM survived because ARM is an embedded processor, and PPC survives as an embedded processor, but Apple's been down the road of trying to shoehorn an embedded processor design into Macs before, and ended up migrating to x86.