That was when FASA still owned all the rights to both Shadowrun and Earthdawn. Since the IPs are now split, there's a limit to what can be done with the Horrors without touching Earthdawn IP. FASA has the computer game rights to the SR license (licensed/owned/whatever by Harebrained Schemes, I don't know all the particulars), so that could be how that bit happens in Dragonfall. Topps owns the Shadowrun IP for physical products (licensed to Catalyst). I recall hearing people from Catalyst say before that they can acknowledge the prior existence of canon but can't build on it; it's one (but not the only) reason why we haven't heard much Horror stuff in SR4-5.
So, basically the same situation as you see with several other similar IP conflicts, then. Though I expect they can most definitely do what, for example Marvel did with Age of Ultron in including Scarlet Witch and Quicksilver, both of them definitively characters tied to the X-Men IP, for which the film rights lie with Fox (until people wise up and stop going to see the films, so they'll stop making them, the rights will revert to Marvel like the Hulk did, and we can get things like Wolverine as an Avenger, or better yet stop Sony from rebooting Spider man every few years) - Basically they can use the characters, since they are established in the Avengers source material, and therefore are ALSO part of that IP at the same time, as long as absolutely nothing is mentioned of their X-Men ties, backstory, etc.
Which would theoretically allow the use of Horrors in SR, where they are established as part of the setting, so long as no references to Earthdawn, their previous invasion attempts, etc. are included. Which I imagine is how Harebrained did it, as they are simply named, and what they do once they get into the world in in 2057 described, with no references to any context for them beyond their role in Dragonfall. With a computer game or a card game that kind of thing's pretty easy to drop into the setting sans-backstory. Incorporating them into sourcebooks for the P&P version though? For that, anything you use has to have a load of extra contextual information for the GM on how this particular plot element fits into the universe, so yeah, I could see them being left out of those books for that reason.
(*edit* Now I'm imagining the same scenario if the "Buffy" and "Angel" Licences were split between owners. And new Angel products could have a "Slayer" in them. Because the setting has Slayers as an established plot element. Hell, even one called "Buffy". But not specifically the same "Buffy The Vampire Slayer" who appears in her own line of products, created AFTER the IPs were split. Just like new ED or SR products could both reference Alamais, but only SR could refer to Lofwyr, whilst ED would probably just about get away with mention of Alamais having a "golden-scaled brother".)
BUT BACK ON TOPIC...Yeah, even if they hadn't stated it on the contest page just the existence of the contest pretty much guarantees a mission expansion. I expect it'll include the Catalyst-selected winners for the organised play, as well as Close The Portal and Into the Ork Underground. Hopefully at least one more scenario with a new boss.
I do agree that there is a lot of potential for that, both in the game mechanics and in the universe setting.
You forgot to mention "AND IN ALL THE EMPTY SPACE IN THE GODDAMN BOX!" ;p
I still think 54-card decks being the exact number needed for introducing new runner roles works perfectly, whether by coincidence or design.
Some obstacle expansions would work nicely too, with more variation in their special rules. We have a few nice unique ones. More would of course be welcome. And as I already said, given how we've already seen individual crossfire cards, new supplementary decks cannot be out of the question.
Hey, even if they don't do new roles, replacement decks for each role could work. a deck of new Black Market cards specifically focused on replacing the existing Mage spells with Blood Magic, for example. Or replacing a bunch of the weapon cards with cool cyberware. Give each card new, different abilities, distinguishing it from the regular deck for that role, and you bring something fresh to each of them.