There are now apparently images starting to leak for Tyranids. I am still assuming that these are very early pics, ( I still expect this release the first Saturday in January), however, it does give some credibility to the idea that we may be seeing Tryanids in December. I am going to imagine that we will find out shortly.
As you can see in the pics, there is definitely a secondary weapon option for Hive Guard. What do you think?
By now this image is out everywhere, and here are a few of the sites that are hosting it.
http://40kwarzone.blogspot.com.au/
http://www.lounge.belloflostsouls.net/showthread.php?33545-Tyranids-Rumor-Roundup