I was slightly hopeful, but I think eGPU is a dead solution. Apple silicone is clearly at pace with the competition. I had a 16" 5600m intel I sold a few weeks ago. I also had a Blackmagic eGPU Pro Vega 56. The 5600m was so good I stopped bothering with the eGPU when I bought that intel 16. I think these new notebooks will put eGPU's/TB3 throughput to shame. If apple's benchmarks are to be believed, it sounds like my new 32-c GPU will do circles around last years dGPU 5600m.
I need to sell my BlackMagic Pro! If I still have it when the new 16" arrives, I'll try it, but I'm sure it still universal AMD kexts will still be missing.