I'm rather enjoying what GW are up to at the moment with Nagash in their WFB line. I've run undead armies since they were just undead armies, so it's kind of nice to see things go a bit full circle, and it's fun to see Nagash again, all grown up.
Where this links (tangentially) with 40k is that GW's "return of Nagash" storyline got me musing about GW's approach to the Necrons, and the C'Tan in particular.
The old Andy Chambers Necron Codex is (in my opinion) a bit of a GW classic, hitting the 40k tone beautifully, and introducing a fully workable Necron army in an interesting and fun way. It certainly wasn't perfect, in that if you didn't have one of the four named C'Tan, your army was a bit generic, but it remains one of the best codices written, in my view.
Many people disliked the more recent (Mat Ward) codex, and I have my issues with it, but it isn't as bad as it's sometimes made out to be; on the whole I still like it. Mat Ward gets far more than his deserved share of internet hate, in my opinion. The Codex is strong on allowing players to create interesting unique armies, and has a considered, open and nuanced take on the motivation of different Necron factions. It's often characterised as "tomb kings in space" which is in my view a fair if double edged criticism; it's true, but then tomb kings are a fun and workable concept/stereotype. I dislike some aspects of the writing, which can come across as a bit cartoonish, but on the whole it's a solid piece of work, background wise. (note I'm not talking about the rules themselves anywhere here, that's beyond the scope of what I'm discussing.)
Anyway, my point here is that if we're doing "the return of Nagash" why not do a "return of the C'Tan" storyline? The C'Tan occupy a similar position in the 40k canon to the position held by Nagash in the WFB canon; the instigators and creators of an undead faction. You could have the four "named" C'Tan (Deceiver, Dragon, Nightbringer, Outsider) return to 40k in the same way that Nagash has in WFB.
Under the newer codex canon, the C'Tan have been shattered into dozens of "shards", though Mat Ward left the background sufficiently open to (in my view) permit GW to reintroduce more powerful named C'tan.
Imagine: a new giant plastic C'Tan model, created using GW's splendid new CAD technology, configureable into any of the four major C'Tan. Just look at the new Nagash miniature for an idea of how adept GW had become at utilising negative space and flowing, floating, silk like features in three dimensions. All of these features would work brilliantly with the floating C'Tan.
Imagine this miniature accompanied with 2 new Codices: one for "tomb kings" style Necrons and one for reawakened C'Tan forces - the "Vampire counts" Necron army. The Necrons are factionalised enough to permit two entire major subfactions: those who support the reawakened C'Tan, and those who fight to defeat them in revenge for the death fo their souls.
You could roll in some interesting new miniatures for the "vampire counts" Necron faction: lesser C'Tan fragments as Elite infantry or generals for the C'Tan armies. For the pure Necron armies have special C'Tan slaying heavy weapons, or portable Tesseract vaults capable of imprisoning them. Perhaps even bring back the Silent King as a named character (a Settra analogue) for the "Tomb Kings" perspective on 40k.
I'd buy all of that little lot GW...go on...give it a go!