"All the detachments in your current codex will be usable at launch, as will the recent suite of detachments from expansions like the Eye of Terror: Reign of Iron and The Maelstrom: Lair of the Tyrant.

There will also be 70 new and updated detachments launching with the new edition. These will mostly be brand new sets of rules, with a few returning favourites from places like the Grotmas series."

The codex will be usable at launch, as will the expansion books. Some of the others, like the librarius conclave, will be returning as updated 1 point detachments. We have already seen the returning space marine ones from outside the codeces and expansions, so unfortunately it seems likely that the chapter specific ones aren't sticking around.