IP/licensing.

I would argue technical reasons too. x86_64 is a huge and complicated beast.

And cost. Making something you can license to others and/or sell to 250000 users each year has a completely different cost compared to something you use only on your 20000 machines (source: [1]). Macs are already overpriced, I don't know how much Apple could sustain an in-house production of proprietary chips without hitting their users; they're probably going to ARM.

[1]: https://www.idc.com/getdoc.jsp?containerId=prUS43495918

I think you might have misread the table at the page you linked. Above the table, it says "Shipments are in thousands of units." According to the table, Apple shipped 20 million notebooks and desktops last year, not 20 thousand.

Doh... Same proportions but yeah, damn language barrier, over here the comma and point meanings are reversed compared to English. Thanks!

And the fact that Apple can already beat x86 on speed per unit of electricity with its own architecture.

that only matters for large data centers and mobile. for laptops and desktops raw power matters.

Uh, actually not. It matters tremendously for laptops.

Shouldn't the patents be expired by then?