While its a growing trend to have the rules come with a new model release, there is speculation that the rules for the new Tyranid models will be coming inside the Blood Angels vs Tyranids campaign, or possibly a new White Dwarf Compendium rulebook.
Whispers are also pointing towards an FAQ update with the rules for the new Tyranid creatures in it.
Please remember that these are rumors.
via an anonymous source on Faeit 212
In the rules for the Sporocyst it says "can produce a single Mucolid spore (pg 52) instead". The rules for the Mucolid Spore are on pg18 of the White Dwarf. This might point towards a White Dwarf compendium or the rules being in the campaign book.
Also, the Tyrannocyte box comes with 6 Spore Mines, and the rules for all the new Tyranid creatures will be added to the FAQ as they are released for sale (not preorder).