Earlier this year, it was reported that Dishonored developer Arkane Studios was working on the long-gestating Prey 2, taking over development after Human Head Studios was rumored to have been booted from the project. However, at this year's QuakeCon, Bethesda confirmed that this is not the case.
Human Head Studios is still in active development on Prey 2, which, according to Bethesda marketing and PR head Pete Hines, has been repeatedly delayed due to it "not hitting the quality bar that [it] needed to." These sentiments echo Hines' previous statements about Wolfenstein: The New Order, which was recently delayed as well.
Hines also stressed that Arkane Studios had nothing to do with Prey 2, and is currently working on their own, unrelated project (Dishonored 2, perhaps?). Hopefully we'll be able to gleam more information as this year's QuakeCon continues.
[Source: Rock, Paper, Shotgun]