Prey 2 was announced long time ago, but since that day things went wrong with this product. If I not mistake, Bethesda published a press note and they stated that Prey 2 was still in development. Kotaku have more info about this drama.
Apparently, Bethesda hadn’t spoken with Human Head about Prey 2 for a year, until they told the team it would be cancelled. Meanwhile, Human Head worked on other projects. During that time, Obsidian was working on Prey 2, for at least a few months.
Now, Bethesda has forced Arkane Studios to work on Prey 2. Arkane Studios (Dishonored) will forget the Human Head development and they will start the game from the roots. Prey 2 should be ready for 2016. Some people of Arkane are upset about this decision, but the company are trying to encourage them, because this new Prey 2 will be like a new System Shock.