Current ArcGIS Online (AGOL) for organizations have a check box to require SSL for the organization's site. If this option is checked, then services without an SSL endpoint cannot be used from within the AGOL organization site. There should be a third option to allow hosted feature services and other content to be sent via SSL from within the AGOL organization's site without requiring SSL site-wide. This might be as simple as retaining the HTTP endpoint for the root of the AGOL organization's site.
