I love how the new Stream Manager looks, designers and devs did an awesome work with it :)

I think it would be a bit more efficient based on what others wrote so far if you add sliding panels.

Currently you can move panels to place them in different areas - cool. Now if once placed you can click on them to have them expand and collapse you can keep the design minimal and show a lot in the same time.

I see few people have ideas about Stream info and Stream Health being available. While I love the action buttons, the Stream info would (in my honest opinion) be a great example when the slider would work best.

You just expand it to change it, and then collapse to finish. Also apply button would probably be best with something as CSS{position:fixed; top:10px right: 10px } so you can change title and without a scroll apply it. Boom done, lets make some fun.

Another thing is to have tools such as Stream Health available as a slider as well, which you do not really need to look all the time, yet as soon as you want it, it slides open.

So this is not about which panels to be added rather examples how the sliding panels can help keep the screen nice and tidy yet expending to your needs.

This could solve:
https://twitch.uservoice.com/forums/923137-new-creator-dashboard-beta/suggestions/38764129-bring-back-stream-health
* If you decide to bring it and were looking to keep the dashboard clean

https://twitch.uservoice.com/forums/923137-new-creator-dashboard-beta/suggestions/38764579-ask-before-closing-stream-info-pop-up
* Because it would now be part of a slide in that can easily be changed, so clicks outside do not matter

https://twitch.uservoice.com/forums/923137-new-creator-dashboard-beta/suggestions/38764438-stream-info-should-be-available-as-a-panel
* Well it would be a panel :)