we're just not currently in a position to do that though. The "Grace period" that happened during the PPC to x86 days was because x86 could essentially emulate most of PPC architecture at the time without any performance hits. OSx up until Lion (I believe) was actually running an emulation later called rosetta.
for such a grace period to occur from x86 to ARM, ARM Would have to emulate 100% of the x86 architecture, and do so with enough overhead to have decent performance in those applications. Unfortunately, ARM is not designed for that sort of workload and suffers greatly under emulation. This would mean that a switch from intel to Ax CPU would have to be a clean cut. Nothing you own from x86 would be usable until re-written / recompiled for ARM. This is not as easy as it sounds. Look at Microsoft's epic failure at doing the very same thing.
Speaking of Microsoft, switching Apple computers to ARM would also eliminate any user from also running Windows, either bootcamp or parallels. With OSx actually making up < 5% of the worlds operating system usage, you would be cutting out any user who uses Apple hardware, but relies on Windows applications.
Then you get to performance. Benchmarks are good for the Ax series CPu's. But thats benchmarks. Benchmarks are artificial and do not accurately reflect true real world performance and how the system behaves under workloads. Sure, the A10 benchmarks high. for a mobile device it's fantastic. But it's also on par for real world performance with lowest clocked, slowest intel mobile chips. They could "substitute" in for an M3, and maybe an M5, but once you start moving into the i3, i5 mobile chips there's no real competition. Once you start talking about the 4 core mobile, or even the desktop class CPU's, there's currently no ARM CPU in these ball parks. And so far, while there are some ARM based server farms in the world, the performance is highly specialized and once you hit the same thermals, still don't keep up with intel's server CPU's in most workloads.
what this comes down to is that overall, while the A10 is a fantastic chip. Probably the best mobile designed ARM cores consumers can buy. They are no competition right now for x86 based systems.
but who knows what happens in 10 years time. But it likely wont be with Apple's Ax series CPU's as a mainstream CPU. For onee, Apple won't likely sell / license their CPU tech, so the only company in the world using it will be Apple. Which means Apple computers would once again, lose all compatibility with 95% of the rest of the world's software. That itself is just not a wise business decision
