The FAQ on the new content pass confirms that the dungeon packs will be in the crown store:
Q. Will content that requires The Elder Scrolls Online: 2025 Content Pass (or 2025 Premium Edition) also be available via ESO Plus and/or the Crown Store at launch?
A. The Fallen Banners dungeon pack (now live) and the Feast of Shadows dungeon pack (arriving Q3) will both be available via ESO Plus membership or a Crown Store purchase in addition to the 2025 Content Pass or 2025 Premium Edition.
Previously, ZOS had mentioned an announcement of when Fallen Banners would be released there, and/or that it would be after the livestream. Is that still the plan?