Unable to @ mention external collaborators in comments within Office online files

Is anyone aware of whether Microsoft will someday enable the ability to @ mention users who do not belong to the M365 tenant within comments in Office online files? I've attached a screenshot of what this looks like in a Word Online file in OneDrive. 
There are a number of Microsoft feedback posts about this, but it really feels like an unnecessary gap in functionality.

Anyone have any insights on roadmap?