QSFP makes sense on a MacPro platform - and might be where Apple chooses to differentiate (one could dream of an M5 Mega, with four chiplets). The Mac Studio is a general purpose compact workstation that doesn’t need ludicrously fast networking beyond what 10Gbe and TB5 offer. It’s already overkill for the vast majority of users. Top configuration Studios are already a niche product.

Apple already ships an MLX5 driver for ConnectX NICs.

Also given that Apple are using these in their datacenters I think they will ship much more server like hw.