well if you gather all the evidence:
dungeons for mountain biome only in new undiscovered areas
new mob for the location (Fenrig and another wolf creature can be seen in the images)
they have said "something will be lurking in the caves"
various "new" items are in the images; floor braziers, wall hanging etc
crystals are on show as points; so possible new mining resource

they have also said its not the full cult of the wolf content.
This will be a relatively small update that adds a new creature, and some new mechanics along with maybe a few build pieces.