AlwaysOn Availability Groups on Secondary Replica
Out of curiosity, it is possible to place Server B on AlwaysOn and move it to another Server C Asychronous Read Only.


If it's the same databases in the already existing Availability Group, then the only way you could theoretically do this is by re-architecting your solution so that Server B and C were in their own cluster and utilizing distributed availability groups from Server A.

I would not do this.