Using a Windows Server 2012 R2 Server as a PDC via remote location
The main issue with implementing this is that your company's domain controller is in a cloud environment that then heavily relies on a stable secure connection.
I think its not best practice to move a DC especially a PDC into the cloud because if the connection to the internet or datacenter fails then your network is S.O.L.
If this is direction you want to go I think best practice would be to establish redundant connections from each branch to the cloud, and have a plan and procedure in place in the event of connection outages.
I suggested having all branches have the connection because if one of the branches loses connection to HQ, or if HQ suffers an outage all branches are inoperable.