I wonder if you've discussed this with Chadori, Mikal and other big addon makers? Will you provide them with support, ensure that their addons get converted before the deadline?
In my case the answer is no, the only response so far has been to deny a suggestion request for SDK V2 to support the ProUI addon and then no further response after I tried to compromise and be more specific in regard to the response and look for help for another solution. I just got a good helpful response and I appreciate it!
I hope this changes collaboration continues in the near future. I feel like it has been more collaborative in the past w.r.t. SDK support requests and hope that returns.
I mentioned this before, but another proposal, is to continue with SDK V2, etc. for the mainline C3. Add a license for full C3 source availability / no encapsulation / obfuscation in runtime or editor as is the general practice with game engines. The typical user which is the one that will complain about broken addons will not pay for the extra license. The extra license can outline the risk and requirements for the user. This license will allow users to work with C3 in advanced way directly or with advanced addons. The advanced addons will only be able to be installed in the advanced version of C3.
Other engines also have a much more extensive feature set and API (Unreal, Unity, Godot) for both general scripting and plugins, if C3 was at a similar level for SDK V2, it would be more acceptable, since it doesn't I would suggest that C3 takes a different approach for more advanced users.