Derik Hammer digs into a more complex architecture for HA+DR:
The Availability Group will handle the data synchronization between the data centers. Asynchronous mode is recommend due to potential network latency hindering primary site performance. With the combination of these two features, you meet HA with the FCI’s automatic failover locally and DR with manual failover of the Availability Group between sites.
Derik’s conclusion is important: this isn’t the type of thing a brand new accidental DBA should try to build; there are a lot of moving parts here. But if you want a robust solution and have the support people available to handle the relative complexity, this is a good option.