Well, this time it's Intel and not IBM, except Apple owns their own chip designs and has 200 billion dollars laying around.
The kernel would run on an ARM processor, along with all the supported software. Any x86 binary would be offloaded to the intel cpu. Sharing RAM and even the remaining hardware would be nearly impossible I guess. Not sure though. This way it can be like the integrated / discrete gpu design and switch can be done a lot less painfully.
Yes of course, we were doing it back in the 1980s with hybrid 6502/Z80 systems, the Z80 side running CP/M.
The territory that they'd concede though is that expandability and people buying CPUs, RAM, drives and GPUs from non-Apple vendors. But that would buy them continuing to tie professionals down to macOS and then selling them laptops and building hype. Instead I think they're going to ditch macOS and switch to iOS on desktops and laptops and you'll see their laptop and desktop sales shrink and they'll be become entirely an iphone/ipad company. I don't think this has anything to do with supply chain and this is entirely self-inflicted damage because they're prioritizing their walled garden strategy above all else.
And? If any of the handful of people on the entire planet capable of building an ARM capable of rivaling Intel's current x86 designs were hired by Apple, it would be all over the tech industry news sites instantly. 200 billion doesn't mean a thing if it isn't applied properly.
The only piece missing is creating iOS apps on iOS devices, for which they've already created a language and an app to learn programming, then everything we do and know and learn just to keep our computers running is kind of legacy stuff.
The only issue will be major apps like Adobe CS and Office, but even those have iOS incarnations that can potentially reach parity with their MacOS counterparts.
I suspect a Mac running a KBM and Windowing friendly iOS would make a really nice machine.