If we are talking about expected future Apple GPUs, we should compare them to expected future Nvidia GPUs. RTX 3000 series GPUs should be available in most price categories in mid-2021.
You are comparing the median GPU of future Macs to the median GPU of gaming PCs that people already have. Of course the 3-4 years between them will give you a faster GPU.
The latest rumors speak of 16-core and 32-core Apple GPUs in mid-2021. They will probably be used in most MacBook Pros and iMacs. The 32-core model should be comparable to the GPU in a $1000 to $1500 mid-2021 gaming PC, but Apple probably won't use it in Macs cheaper than $2000.
There are also rumors of 64-core and 128-core GPUs in the late 2021 or in 2022. They should be comparable to the GPUs in $2000 and $3000 mid-2021 gaming PCs. The 64-core GPU will use too much power to fit in any MacBook Pro, while the 128-core model will probably be too power-hungry for iMacs as well.
My overall prediction is that future Macs will (finally) have decent GPUs, but they will still be slower than in comparably priced gaming PCs.
I think you're missing the point.
The point isn't about pure power. The point is: how many AAA capable computers are available for developers to develop for? How many computers have a 1050Ti/1060 or better GPU are there? These two are the most common GPUs on Steam which means AAA developers have to develop for them.
Kuo predicts that Apple will sell 35 million Macs/year (20% market share) within 3 years. That's 35 million computers capable of playing AAA games at low to high settings. According to
IDC, the number of gaming laptops and gaming desktops sold in 2020 was 37.1 million. That means in 3 years, 50% of all gaming computers sold will be Macs assuming they don't overlap.
Do you think AAA game developers will ignore 50% of the available market?
And if Macs take 40% of market share in 5 years, then the number of AAA capable Macs will be 70m/year sold versus 37m for PCs. That means 65% of all AAA capable gaming computers will Macs. But the reality is probably even worse for PCs because many people who buy gaming PCs will have switched over to Macs if Macs continue to increase market share.
Thus, Macs are poised to become the #1 platform for AAA games.