The amalgum of rumours seem to point to:
Combined armies ala End Times (So your DE should be as fine as my WoC, but will eventually be part of a larger Elf faction, same with Chaos, and forces of Order in one iteration or another.)
multiple modes of play, one is a skirmish game called Age of Sigmar, and another seems to be very similar to 8th ed.
Aren't the rules in the GW End of Times books? I was going to read the Black Library End of Times. I imagine the rules have consequences in combining armies. I think parts of the Dark Eldar would be potentially attack their allies for example.