Is millions of files & many TB *mirrored* to local file systems within scope for Drive for Desktop?

[JRF]

Question:  Is having millions of files and terabytes *mirrored* to local file systems within the design parameters of the new "Drive for Desktop"?  

More philosophically:  will the concept of "backup" disappear when "Backup and Sync" becomes "Drive for Desktop"?

Context:  I use "Backup and Sync" as a core piece of infrastructure.  While we make extensive use of Google Docs, the majority of our files are PDFs and MS Office files.  Many of the MS Office files are point-in-time snapshots of Google Docs.  We use Google Drive as a central archive for all of these files.  I found that Google Shared Drives have file count limits (400,000) that are too small for these archives, so I share projects only as shared *folders* in my My Drive. 

My total file counts is over ten million and several TB.

I keep a small set of *current project folders* on my laptop.  When a project or time period ends, I stop syncing that folder, so that the files are no longer on my laptop and instead are *backed up* in Google Drive.

For redundancy, I have multiple geographic sites with workstations running Backup and Sync that download the entire My Drive to an external disk.  These sites also run Apple Time Machine backups to a second external disk.

I love Google Drive because it unifies three things: (a) central nexus for files created on my computers or in the cloud, (b) searchable index of those files, and (c) distribution point for getting files to multiple backup sites.

How should I interpret Google's move to "Drive for Desktop"?  Is my usage pattern part of your target vision for what you want to support?  Or is having millions of files and terabytes *mirrored* to local file systems not within the design parameters of the new "Drive for Desktop"?  

Here's another way to ask the same question:  which of these two choices would you recommend as more reliable?

(1) Use "Drive for Desktop" to mirror a My Drive with 10+ million files and several TB to offline storage on half a dozen different computers.

(2) Use cronjobs to run rsync to mirror between sites and have just one of those sites syncing with Google Drive so that files in Google Drive get into the backup sites and files added to the offline sites become searchable in Google Drive.  

(Anecdote: I believe strongly in using tools in the way that their designers/maintainers intend.  I once had a disastrous experience with the non-atomic file moves in garbage that is Dropbox because I didn't realize that they weren't intending to offer a real file system.)