I honestly don’t expect metal performance to improve substantially if at all from where it currently is. performance tuning can just as easily be about stability and feature support as it is about raw speed.
Outside of maybe a few people, I don’t think many are making the claim that these pro and max gpus are about beating the competition. its more about apple finally giving decently performant options wherein there was previously no real path forward on apple hardware. (We had zero gpu rendering support the past few years, so literally anything is a step up)
The Mac desktops will probably double or quadruple the gpu cores, which would at least in theory close the gap somewhat on a 3080 or 3090. But like you said, you could always double up on those cards if performance is king and money is not an option.
I doubt apple is going to fully match or beat Nvidia’s best offerings unless they start throwing dedicated raytracing cores or something into their machines. I think their DNA is more in the photo/video editing world for the splashy benchmark results, anyway. Other than that, for these laptops at least, I think the goal was to balance some relatively ‘good’ performance across a variety of tasks in a portable, energy efficient package.