There's a lot of hope behind this, and unless Apple decides to open-source their plugin format, there's nobody to compete. VSTs are so bad that most DAWs would adopt an alternative with zero additional features, simply because Steinberg's positioning is a pain for the community. I reckon this little format has a chance, but it remains to be seen whether it's successful or not.
It being MIT licensed also gives it a much better chance of getting integrated into all sorts of smaller DAWs and cheaper ones too that might not have wanted to deal with all the nonsense that comes with VST.
So ... consider the possibility that the fundamental data models in both Live and Bitwig make it hard to support ARA2, in an inverse of the way that Live (and later Bitwig) had clip launching for 16 years before any other DAW.
They have rewritten their codebase back 10-15 years ago (or at least refactored it heavily) and have made videos about it.
Ableton adds pragmatic stuff. They have tons they could add without running out of ideas for those for 50 years. A new format is not one of those (and will have small workflow impact on users anyway).
Examples: ARA support (somebody already mentioned), melodyne/flex/style vocal correction, soft track re-arragement (versions), and 50 other things besides...
The actual API isn't terrible, if you can find it under the huge pile of abstractions and classes and toolkits built overtop of it and shipped in the SDK. Steinberg's SDK has too many normative lifestyle assumptions. From VSTGUI to their own COM-like component model to the huge mile high pile of macros they've thrown onto CMake, it's just ... pushy, its own universe. Doesn't play well with others.
I built for it because I wanted what I was working on to be workable in the majority of DAWs. But as the thing I was working on went from "maybe a $$ project" to "I'll open source this", I'm not sure I want to invest anymore time in VST3.
I could see porting to CLAP instead.
I think Live will support it at some point.
Cubase and Logic... I doubt it.
Looks like it's only a matter of time until others pick it up.