There has been an interesting trend occurring lately in the new Codex releases - Apocalypse units are starting to show up in normal 40k games.
If you look back at the 40k armies that have been released since 5th edition the majority of the armies have included a unit that looks like it came right out of Apocalypse. The two biggest example of this is the Guard codex with its Valkyrie and host of new tank options and the new Tyranid Trygon (not to mention the Tyranofex).
If you look a bit closer you will also see a few Apocalypse/Forge World units sneaking in to other armies. I would definitely say that Thunderwofl Calvary would fit the bill for this. They are an entirely new unit that just screams Apocalypse to me. The Chaos Daemons and Space Marine codex don't really have anything that fits the bill on this front but they were release right after fifth came out.
Looking forward the Blood Angels look like they are going to be getting a few units that are inspired by Apocalypse and Forgeworld. The Tantalus Lander is right in line with the Valkyrie and the rumored Chaplain Dreadnought is right out of an Imperial Armour book.
Beyond that? Who knows. I doubt we see super-heavies any time soon but I would have also said the same about the Trygon last year so who knows.
With Dark Eldar, Necrons, and the Inquisition on the distant horizon who knows what kind of new kits we will see by this time next year.