FW want to convert more of the deamon engines and superheavies from epic in to 40k sclae. however, simply blowing up the old models is not a realistic option, so they would need to be completely redesigned, probably keeping little more than the original name. they also pointed out that scale ratios in epic do not work in 40k. mostly, especially on tall models such as titans, they are too short! And the taller the model, the worse this difference is (so my warlord at 40+ inches isnt too far off what they should be)

Another few bits and pieces: Talking to Darren Parwood regarding the Imperial Avenger; he said that it is very much a ground attack craft designed to elliminate tanks and armour. Thus sitting well in the family of Thunderbolt, Marauder Bomber, Marauder Destroyer... Darren said that he had originally set out to re-design the Lightning, aiming to bring it's aesthetic more in line with the aforementioned list to create a more coherent STC aesthetic, it would not be a replacement for the current model, but an alternative varient. With the Imperial Avenger taking over as something new and exciting he was not sure when he'd be working on the Lightning Varient again, but was optomistic that it'd be sooner rather than later.

EDIT: Darren talked alot about developing the lightning around a single central engine, which sounds pretty cool.