I guess you can expect nearly all Flagrow and Reflar extensions to be compatible.
I'm not sure if we made an official comment supporting that as Flagrow but in particular Bazaar has already been prepared for it. The other extensions will likely follow. Unless there's some big challenges I guess we will have made all extensions compatible in a few weeks at most. I think we have one or two officially deprecated extensions, these will not be updated.
Reflar just made a statement that they are entering feature freeze in preparation for beta8, so I suspect most of their extensions will be made compatible as well.
MigrateToFlarum extensions will also be made compatible as soon as possible (might hold until one of my clients actually contacts me to migrate to beta8 themselves).
As for my own non-Flagrow extensions only the emoji picker will be made compatible at first. If somebody needs the WeeChat extension compatible with beta8 feel free to reach out to me. Comic Sans might get an update next year ?
Please take all that with a grain of salt and watch for messages from the dev on the various extension discussions.
MikeJones Might be a good idea to prevent all of us users making posts that say "will x extension be beta 8 compatible?"
Agree with you. I'd add that I'd really thank everybody to wait for a few weeks after beta8 to ask again whether/why an extension is not (yet) compatible with beta8. Most of the devs update these extensions in their free time so update might not be immediate. Thanks ?