They probably have a lot of customers still demanding Intel CPUs. Mac minis are often used in server farms as build servers and there are many companies that would require Intel CPU there for some time.
Seems pretty obvious to me that there will be another more higher end variant of the M1, though maybe the only difference will be the amount of RAM, the number of GPU cores, the number of supported USB4 ports or something like that, not raw CPU performance.
Either way, it seems obvious to me that the M1 is their low end Mac chip.
That will be interesting to watch.
Server farms are going to switch rapidly, one leading Mini server farm just announced a 600 unit starter order, and the CEO noted that Big Sur also made significant changes to licensing to make its use in server farms easier.