SQL Server 2014 - AlwaysOn HA - Always Synchronizing
Since you have configured AlwaysON as Asynchronous, it will be in synchronizing state.


  Should it say Synchronized at some point?


If you want to do a planned failover, you should alter your availablity group to synchronous and then do a failover.

When you change the synchronization method to synchronous and when the secondary has catch-up with primary, it will show synchronized.

Refer  to my answer : How far is secondary behind primary ? as well as AlwaysON professional blog - Determine Availability Group Synchronization State, Minimize Data Loss When Quorum is Forced