Domain Controller on Multi Subnet Always on Availability Group
Suppose if the Primary site goes down the server on the DR will still be able to used cached credentials. 


Assuming the DCs and the rest of your infrastructure will fail over to DR by some other means, your DR SQL Server may not be usable until that happens.  So the AG will give you a  very good Recovery Point Objective (RPO), but the Recovery Time Objective (RTO) won't be any better than a VM failover.