@Gargron The likelihood of such an arrangement lasting more than ~24 months is close to zero. They don't care about harvesting data from Mastodon. They care about capturing the marketplace by eliminating Mastodon as a competitor by "offering" the ability to reach/ingest content from users here from a threads account because their focus is on being the preferred hub over Bluesky and Mastodon.
Once they have captured a critical mass of the ex-Xitter audience, they will lop off ActivityPub and do what Xitter did (and Instagram before it, and pretty much any critical mass audience capture entity) -- you want to see things on threads, then you have to join threads.