I'm a huge fan of what Microsoft is doing here to A) make Yammer feel more part of the overall Teams experience and B) add features that change the value prop for using Yammer in Teams (i.e. Stories and Storyline). Today, we are often faced with governance decisions on our associates posting personal stories in the All Company community or others where the content doesn't quite fit. Storyline gives self-expression a natural home and makes the "Following" feature much more useful. We're also excited about the multimedia aspect of stories (i.e. Facebook, TikTok) which is just more natural for our younger associates.
I do agree with other comments here about the brand complexity... this increases the challenge of giving our associates a simple mental model for what to use when. We would appreciate help explaining Viva Engage to current Yammer users (both copy and visuals)... but the fact that we even want that suggests it's a bit complicated. I keep coming back to this... Teams is our central surface for teamwork (inner loop) and engagement (outer loop).