I think everyone is starting to understand the bad news, which is that Webform 6.x is going to break some code. This change will result in fatal show-stopping errors, which are easy to fix. Developers need to apply the implementation pattern documented in the change record. Because most patches and changes to the Webform module do not alter a class' constructor, there is some good news: We should be able to maintain a Webform 8.x-5.x and Webform 8/9.x-6.x branch at the same time.