We know that this will be released in may alongside the norsca update, so that is the answer to your question.
The next free LL we get is for the lizardmen, and as flc lords are released alongside dlc the next dlc is likely to be a HE/DE dlc (if it was a lizardmen/skaven one then we would have 4 skaven and lizardmen lords, while with HE/DE we would have 3 for every base game race). However, that's not to say they won't get any love.
They used to do mini campaigns with race pack dlc but even if they did continue doing that, having one for the elves are out of the question as they are a base game race. Originally posted by THEDOSSBOSS:Well CA don't exactly do expansion campaign dlc for the warhammer series.