I looked at many videos from GenCon and demos. At this point we know some mechanics but there are 2 very importent news that maybe someone did not wrote here.
1 - the start is this core set Undead vs Humans but already at this point there are new fractions in development and will come in the near future
2- the core set is only 50 points for each army but at tournaments the armies will be 100 points so You will neeed 2 core sets to play in organised play
There is one more interesting thing the 1st wave will have new units. A standard Bearer, Musician, a new hero for each army that will come in a pack with 2 models - ounted and on foot. Also the 1szt wave will ad magic users so a Magician for humans and a Necromancer for the undead. Most likely also all the units from core set will have additional packs with them with different sculps. That's a good news,
cheers