Not trying to make a sales pitch, but we developed a product that provides the static embedding and dynamic linking features of PowerPoint without the need for SharePoint Slide Libraries. Slides can be stored locally, on network shares or FTP sites. We are adding direct capabilities for DropBox, OneDrive, etc. in a future release. Not sure if it will fit your needs, but you can try it out for free.
Hope this helps and I apologize again for mentioning our product here, just trying to help.