A Tyranid codex is being worked on, and it looks like it will be sometime next year at the earliest. This does not mean that there will not be any updates for our favorite bugs before hand, but that a codex is at least a sometime around a year+ away.
Please remember that these are rumors. Salt is always required.
via an anonymous source (that must remain so for obvious reasons) from the Faeit 212 inbox
*Tyranids are coming. Probably after Orks sometime next year.
*Carnifexes are getting a big boost
*Deepstriking emplacements for shooting and increasing synapse ranges
*A new Spider-like Pysker Monstrous Creature
*Background being expanded with some sort of connection between the old ones and C'tan being worked on.