I think it would be best to leave the current look of Breeze alone and use a different repo for the new version of Breeze. We also need to come up with a name for the repo. We will have to decide whether or not to use a completely different name.
The downside of course is that it could take years to roll out the new theme if we make it a separate fork/codebase. If we do go that route, I'd like to try for an aggressive timetable and not get stuck in analysis paralysis and shooting for absolute perfection.
What should we call the new version of Breeze so we can use it as the repo name? I thought about Breeze 2 or Breeze 6, but those seem like they might cause confusion for users, especially if distros continue to package the old version of Breeze along side the new version.
Zephyr is super appropriate—a breeze from the west—but the name reminds me of generic military FPS games for some reason. Also what @cblack said.
I like gravity, just because it sounds powerful and it's a surprisingly uncommon name. I just hope it doesn't sound too grave.
Kinetic could be appropriate if we do some work on the animations for the new theme.
According to Wikipedia, dynamos are obsolete. I don't think I'd want the new theme to associate with something obsolete.
Equilibrium could represent our desire to make the new theme less flat.
Serenity isn't that bad, but it sounds like something you'd read in the caption of an Instagram post and it doesn't sound very unique or inspired.
Harmony seems pretty safe, but it also doesn't sound very unique or inspired.
I think it should be something like a Material Design or Microsoft Fluent Design, the completely new KDE Design*.
KDE Design* would have comprises a recognizable and unique style, so that KDE Style not confused with Windows or macOS.
How about the icons? With new name we could to evolve a Breeze icons.
I mean, look on Gnome HIG everything is much better than on KDE HIG, i dream about an ideal KDE design like on Gnome or new Deepin V20.
I don't think we should change the icon style to be more rounded. I don't think it would be worth the time and effort required. I also don't like the Breeze Round Corners theme. You can't just round the corners and call it a finished job. Many of those objects depicted have ruined proportions and jagged edges from being clipped.
I think discussions about style are off topic here as well. If you want to talk about changing specific things about the style, T10891 is the place to post ideas.
Getting back to the topic of naming: I just did a real quick search for "zephyr" or "zephyr style" and could not really find anything obviously style related. Therefore I would suggest to use Zephyr as the new style name.
These are the 2 Zephyr styles I found. They're not very popular and haven't been updated since 2015. I guess it wouldn't hurt to use Zephyr.
Apparently there's a project by the Linux Foundation: https://www.zephyrproject.org/
I've also thought about Neo Breeze or Breeze Neue