Shannon,
I think talking with an Esri consultant would be a wise move particularly dealing with the server/publishing side of data access. However, I can share a little bit of my County's ideas regarding Cloud vs. file server storage.
I work for local government and my department has been asked to move all of our documents to SharePoint/OneDrive storage. As the GIS lead for my department, here is what we've sketched out as a plan for the GIS-specific files.
Use SharePoint/OneDrive for Output PDFs or Microsoft Office documents (i.e. analysis results/reports/documentation)
Use SharePoint to store published/finished map or output products, especially if stored as Microsoft Office document formats. This can include copies of any metadata for GIS datasets exported from the XML version that accompanies the documents. That is where cloud-storage makes sense - SharePoint or OneDrive make it easy to share/edit/comment on one copy of a document rather than emailing multiple copies.
Use file geodatabases on a file server or ArcGIS Enterprise for editing source GIS datasets
For editing data...depending on the number of edits and whether they are concurrent or separate, we use ArcGIS enterprise/server for core data (i.e. the important datasets that everyone uses for daily operations). The advantage of using Enterprise is its support for versioned data (makes it much easier to restore a backup in case of a GIS software crash or editing error/mistake operation and concurrent editing. However, you have to have a staff person to support the administration of that server, so some organizations prefer to just use file geodatabases for data editing.
Use ArcGIS Online/ArcGIS Enterprise (Portal) or file geodatabases on a network file server to share reference data
For storing source GIS datasets for reference (i.e. the stuff you view but don't regularly edit), you can either use dedicated file servers/network drives with file geodatabases or ArcGIS Online/ArcGIS Enterprise (Portal). We have started seeing the advantage of ArcGIS Online and Portal for sharing data and maps internally - it functions/benefits in much the same way for GIS data that cloud-storage works for collaborative sharing of Office documents.
If you have a series of standard layers that everyone always uses, you can store those in read-only file geodatabases with layers or map templates that point to those data sources...or you can publish them to ArcGIS Online (even for internal use) and then people can add them to ArcGIS. Admittedly, this is much easier in ArcGIS Pro than in ArcMap/ArcGIS Desktop, but it does have its advantages.
These are just some thoughts I have had based on my experience migrating from the file server/disk-based world to cloud-base storage. Hope it gives you some food for thought as you reach out to Esri or talk to other consultants.
