It's worth noting here, as I had this trouble a while ago, that most of the kits that are unavailable are due to one specific model being unavailable out of each of those kits, like the Sister with Power Maul being unavailable and therefore making the Retributor Squad as a whole unavailable, even though the rest of the individual models for the Retributor Squad are still available.

So the list is really only about 6 or 7 models that are no longer available.

HOWEVER.

A month ago when I checked, there were only 2 models that were set to 'No Longer Available'. So, now that there are like 7 that are No Longer Available, that's really a step up. Most of them are character models, it looks like, so the pickings are getting slim, fast...

That's a good sign.