It’s hard to predict but the extinguish part would come from bigger non-Threads instances implementing compatibility with Thread-only extensions (in the interest of their users, or for money) and fragmenting the community. Threads then becomes the defacto ActivityPub standard. Maybe some instances stay true to the standard but with extremely reduced communities because now they can’t see what other instances are publishing. So now you have to decide between your ideals and your social network. At best, you’re back to square 0.
It’s hard to predict but the extinguish part would come from bigger non-Threads instances implementing compatibility with Thread-only extensions (in the interest of their users, or for money) and fragmenting the community. Threads then becomes the defacto ActivityPub standard. Maybe some instances stay true to the standard but with extremely reduced communities because now they can’t see what other instances are publishing. So now you have to decide between your ideals and your social network. At best, you’re back to square 0.