Will the Tyranids affect campaigns and territory control?

Absolutely. From time to time, the Tyranid threat spreads and Capillary Spires burst out of the ground, conquering outposts and strongholds. Each faction must do what they can to flush the Tyranid threat out of their territory or risk losing it to the Great Devourer—along with any benefits that come with it!

Naturally, owning more territory draws more attention from the Tyranids, but these ravenous monsters are a threat for every faction to manage as campaigns go on.