Don't think it makes sense for them to re-build their x86 version of MacOS into utilizing AVX2 in 2022, something Apple Silicon macs gain no benefit from, if that was the case. Seems to me they're still on the motto of trying to make as good products as possible as that will retain customers and win out in the long haul.
When selling products, especially expensive products like the Mac Pro, you have an obligation to maintain the business
relationship with your customers. This means ensuring that your products work at their best, for the duration of the lifespan.
For business machines, the expected lifespan, should be no shorter than 4-5 years.
If you buy a new computer today, do you expect it to get slower, to the point of being unusable, in two or three years just because they’re new products available? Or, would you expect that computer to work well, for the intended lifespan, regardless of when new products are released?
In any other field, consumer advocacy groups would be up in arms if, say, Tesla did a firmware update that resulted in significant mileage reductions between charges.