Well, considering how well the M1 variants are performing in the performance/watt category and this is one major cost factor for data centers, I would assume Apple by all means is going to use their own chips in the future. And then there is no good reason not to sell a tons of them to anyone who is willing to pay Apple prices for server hardware. (Which aren't that bad, compared to other server hardware prices)
But this might a bit in the future as they barely can make enough of them for the MacBooks. I even would assume that the launch of the other computers in the lineup has been put to a later time to be able to keep up at least a bit with demand.
Anyway, it’s academical because I don’t see them doing that. Expect maybe to power their own datacenters, but then we’d never hear about it.