[theluketaylor]

The modem business from apple represents a huge amount of leverage over intel. It doesn't really matter what part it is, if you sell 50 million of something per quarter you're going to do whatever it takes to keep that business. Even if apple stops buying x86 processors modems alone make them one of intel's most important customers, especially when intel is trying to grow their modem business.

thunderbolt is a hurdle to arm macs but I don't think an insurmountable one. As you mentioned Intel already committed to opening the spec and if apple can't negotiate getting tunderbolt host controllers tossed in super cheap and forcing intel to honour its own commitments with modem sales they don't deserve to be valued at 1T.

TB is one of the big reasons I think macbook would be the obvious 1st mac to switch. It currently only has USB-C (no TB) and it's due for a refresh since the lack of touch id makes it an outlier.

When apple switched from ppc it was a multiple year effort and I don't see any reason a switch to arm, whether it's a full move or particular products would be any different.