Again, you're citing the source control system as the primary feature. TFS is an entire application lifecycle management suite, not just version control. You seem to (continue to) ignore this. Its closest analogue is probably the entire Atlassian family of products.

On TFVC:

> it sends way WAY too many files up and down constantly

It sends literally zero files anywhere until you interact with the server, as any sane server-based version control system would do. I don't know about your workflow but I don't know what you consider a reasonable amount of I/O to sync a workspace. You can elect "Local" workspaces since around TFS 2012 which can work completely disconnected if you choose.

> branching/merging is expensive as all heck

It's folder-based branching and can be done very quickly/cheaply if you don't store your entire company in source control. And how well does Git handle large files? Git is opinionated on branches and creates them cheaply/quickly; TFVC evolved from CVS-type systems where this was not the prevailing mindset, but again I don't know what you're considering "expensive." Maybe where you work?

> even Microsoft's internal teams are utilising Git and Github

Which isn't evidence of anything other than it's their current tool of choice. That has a lot less to do with future direction of their enterprise products than you're assuming here.

> Microsoft's own consultants

> Microsoft's internal teams

> the Windows team within Microsoft

Do you have insider info or are you just trying to sound like you do?