What if Intel makes TB4 with PCIe 4.0? Then it will be a different story. There is a reason why Intel made TB3 royalty-free.
...and the most likely reason is that TB3 simply wasn't working as a way of locking people in to Intel hardware. Intel's problem with TB is that USB 3 is good enough for most storage and other peripherals - and the top-end users still need proper PCIe slots with 8 or 16 lanes (....and which will probably still have 8 or 16
faster lanes when PCIe 4/5 take off). Clue: Apple have just dropped their TB-only Mac Pro cylinder for a more traditional tower design with a ridiculous number of PCIe slots...
Meanwhile, there's a reason why the brand spanking new Mac Pro's slots are still only PCIe 3, and it starts with an "I"... AMD have already launched PCIe4 slot support. Intel haven't. So I wouldn't hold your breath for PCIe-4-over-Thunderbolt.
USB 4.0 wont be available until 2021.
...which is also the realistic timescale for AMD or ARM Macs. (Any hypothetical move to ARM would probably start with either a 12" MacBook replacement or something that was effectively an iPad Pro running MacOS, and wouldn't necessarily need Thunderbolt on day 1 - Personally, I suspect Apple have decided to go down the iPadOS route rather than MacOS on ARM).
At this point, Only Asrock's motherboard has one TB3 while others dont and it's not enough of data that Intel allowed AMD to have TB3.
It is
absolutely proof that you can have TB3 in an AMD system. There are plenty of
Intel-based PC motherboards without TB3, too - TB1/2 got
nowhere on PC, TB3 has got a bit further (partly because the Intel TB3 chips were also a good way of implementing USB-C and USB 3.1g2) but its hardly ubiquitous. Its only Apple who have gone head-over-heels for Thunderbolt - practically forcing people to use it by skimping on ports, internal storage and (until the new Pro comes out) no PCIe slots even on desktops.
The biggest point is that Intel 10nm mobile CPU has integrated TB3. Why would they put TB3 controller in CPU instead of the motherboard since they made royalty-free for TB3?
Er... because its a
mobile CPU and the idea is to integrate everything on one chip...? Intel CPUs also have built-in USB 3.