Bethesda released a statement this morning revealing the delay. "The delay is due to the fact that game development has not progressed satisfactorily this past year," it reads. Despite the game showing "great promise," the publisher is "unwilling to compromise our quality standards to meet a release schedule."
The Human Head-developed sequel to 2006's Prey suffered rumors regarding its cancellation earlier this year – rumors which Bethesda refused to engage at the time. Given Bethesda's track record with shooting down cancellation rumors, that put Prey 2 in a nebulous place for the past month.
Update: Bethesda declined to comment "beyond anything that's in the statement."