There is no "official" version of
Fall from Heaven planned for Civ V.
Ahwaric is planning to make a sequel to his FfH2-based
Orbis mod, for Civ V. You can read more about Orbis 2 (and participate in the discussion if you like) in this thread:
Future of Orbis - Civ5 incarnation discussion
I seem to recalling reading something about the
Fall Further team working on a Civ V mod, but I believe that they are going to create their own world, rather than creating an Erebus-based sequel. I'm sure that they will come up with something very interesting, though, and am looking forward to trying it out.
I haven't heard must else on the topic, but I don't read everything so I'm sure I've missed news. Perhaps others better informed can fill in the gaps I've left.