I can't find any other posts on this subject so I thought I would start one as a placeholder and float some ideas.
I understand that proprietary SQL Server Replication is not possible to/from Azure SQL Database due to obvious reasons (no local MSDB DB or SQL Agent for example).
My best solution so far is for an intermediary SQL Server sitting inside an on-premise DMZ to move data in and out using SSIS Packages. This solution relies upon 'duplicate' licensing which almost makes the cloud-concept academic however, plus at least a working knowledge of SSIS.
Alternatively an Azure SQL Server VM (Iaas) with the necessary VPN configured to connect to on-premise servers using Domain credentials. Again, this negates the WASD (PaaS) concept.