I think they already are.
However, post-Apple Silicon, everything is running on the same handful of systems-on-chips and there's much less variation in terms of CPU, GPU, software compatibility issues etc. between the different form-factors than there was with Intel, so it makes sense for more discussions to go into the "Apple Silicon Macs" forum unless they're primarily about model-specific features.
Bear in mind, that Intel Macs remained on sale for a couple of years after the launch of Apple Silicon - the last Intel models were only discontinued less than a year ago, so it will be 4 years or so before they become "vintage".
I think an "Intel Macs (i-series)" sub-forum will probably be needed (maybe when Apple drops Intel support from a future MacOS release). The Core Duo/Duo 2/Solo machines in the "Early Intel Macs" really are getting "retro", whereas things like the 2020 iMac and 2019 Mac Pro are going to be perfectly capable machines for some time yet.