Guys, I think you need to stop panicking and prematurely selling off your collections.
The Cannon and Organ Gun is "last chance to buy", but were recently added into a mercenary company in GHB19. In my opinion this means they are only getting reboxed to be sold in stores too, since they were only available in the white mail order packaging.
The same goes for Quarrelers / Thunderers and Warriors - they still have their old WFB packaging. High Elves / Sky Wardens have the identical issue, not sure if they will be kept around or discontinued for the sake of the new hinted Hyish "light elves".
Last chance to buy could mean they are emptying their stock of the old 16 man (duardin) boxes. Could also mean we finally get 20 modell boxes for those.
Many of the discontinued Empire character models are resin, they probably will throw those out for newer character models with a more AoS-style appearance (like the new announced Ogre Tyrant). The Unforged however could very well be retired without a new replacement, since the Slayer guys got their own entire Army and can be allied into certain cities anyway.
As some wrote previously, lets wait and see what we get. If they are gone for good, we can still grumble then.