Adding network locations to the Pictures Library did not work. You can not add them directly, because the location is not indexed and adding them using symlinks worked to add the location to the Pictures Library and to the Photos App, but caused the Photos App to crash when trying to access any of the content from the network location.
As for using offline files, if you are referring to SkyDrive files available offline, I am.
Again, I am not ignoring that the functionality has been removed. I just wanted to state this as what may be a temporary workaround for some, as it was for me, and to illustrate that, at least for me, the Photos App is displaying everything I have in my Pictures Library (because some people were stating that nothing was showing up in their Photos App. Not even their Pictures Library).
Hope that clears things up.
Edit: The main thing I wanted to address was really just the issue of people stating that the Photos App doesn't even display content from your Pictures Library anymore.

