We have had lots of rumors lately on exactly what is coming, but I went back to dig up some of the more reliable ones that I have had here on Faeit 212, just to see what was going to happen to the bugs. Now these were from playtesting and so may have changed. However, these are very reliable on exactly what direction the Tyranids are going to be taking.
Please remember that these are rumors from back in August.
First up though, I want to mention that a very solid source has confirmed for me that December is definitely going to be Tyranids. That makes just too many sources confirming this change in the line up. I have to go with it.
via a strong source here on Faeit 212 from back in August
Tyranids, at least at current can ally with themselves essentially.
They have the standard:
2 HQ
6 Troops
3 Elites
3 Fast Attack
3 Heavy Support
And can take an optional
1 HQ
2 Troops (not minimum 1, up to 2, but instead MUST take 2 and then...)
And if they do, it unlocks
1 Elite
1 Fast Attack
1 Heavy Support.
Only an HQ from the core can be warlord.
Then the diversity comes into play.
Hive Fleets now have different rules (think chapter tactics). Your secondary brood can be from a different hive fleet. Not representing two fleets working together, just similar evolutionary strains.
There are also army wide FoC changes based on your Hive Tyrant. Wings give you the option to take Gargoyles as your compulsory troops (so max 2) for instance. Bonded carapace let's you take Carnifex's as elites as well as heavy support (but can't be more than a certain number of points, so they end up kinda baby).
They have some really cool adaptations for skyfire.
Warriors can be purchased as sergeant style upgrades for gaunts and gargoyles. They get the biomorphs of the brood and are not attached like wolf guard.
Tyrannofex will see a points decrease.
Pyrovore will see torrent.
Ranged biomorphs contribute to a model's close combat.
Melée biomorphs enhance a model's ranges attacks.
You take some biomorphs that affect both, like +1 str to both.
But having a gun makes melée better and having melée weapons improves your guns. There's some new synergy there. Mostly for big bugs.
Psychic ability is a lot worse than what it is now, but it'd be difficult to explain and just upset people who don't have the whole picture.