I'd like to throw my use case for multi-camera into the mix too.
TL:DR I need multiple cameras so I can stream the 6 whiteboards in my workspace of chaos and the in-software ability for users' to select which of my streamed displays they like. Right now I can achieve a similar result by signing into the call 6 times but it would be nice to have 1 computer and the Teams manage the multiple feeds.
For my standard 9-5 (Software engineer), my 5-12 job (DBA) and personal work (software design/consultation/contracting/plans to take over the world) with 6 walls all made of whiteboard material. Think Silicon Valley season 6 ep 7 (https://images.app.goo.gl/dASSTmGFB2G5FUEE8). I have a camera pointed at each surface and a computer connected to each camera so if I need to show multiple displays or walk back and forth from whiteboard to chair frequently I have to join the teams call multiple times from multiple computers.
In a perfect world the gallery view would recurse to the level of the user and attendees could see all feeds I offer at once or click into a single feed to go full screen. It is EXACTLY how the app works now (gallery and presenter views) but available one more level deeper- I would have my OWN gallery and user's would select from my gallery which panel they want to go full screen with.
Perhaps this sounds like an edge case but it would absolutely fit the need of all the educators who have spoken up in this thread as well as the folks who are frequently in motion between desk and whiteboard.
Teams would make me so, so happy if this became available. Never even thought to ask. My audience gets quite a laugh when a call starts and they see "Evan has entered the call, Evan has entered the call, Evan has entered the call, Evan has entered the call" over and over for each computer/camera pair I call in from.