Nobody in Hollywood would dare to encourage ask of Francis Ford Coppola+associates to ever do a street racing action movie in the vein of Fast&Furious.
FTFY
That's exactly what Bethesda wanted of Raphael Colantonio and the Prey team. That's probably the straw that broke the camel's back for him.
Story time: While Raf and Ricardo was trying to get what would become Project Danielle off the ground,
he asked "pretty please" for the System Shock license. Bethesda couldn't bother or didn't manage the task, so Raf wanted it to be a new IP. But
Bethesda had others plans. After
failing to find a new developer to keep working on the Human Head's Prey 2 game, they decided to "reboot" the series (in order to keep the Prey IP), and force Arkane to use the brand name against Raf's will (and better jugdment) for their new project.
The bulk of the Dishonored development team was in Lyon. So, in less than 4 years, Raf and the HR team increased the studio's headcount with talented folks, worked with a whole new game engine, and released a full-blown game to great acclaim. Prey 2017 was born. Victim of the terrible Pete "donuts are for closers" Hines' clownshow marketing, hurt by a retarded score from the biggest gaming website in the mainstream media, and still in the shadow of the infamous Human Head Studios/Prey 2 situation, Prey didn't sell well enough.
So it came the time for a new project. Ironically, Raf wants a follow-up to Prey; Bethesda, a new IP. A new game franchise they can milk. So it has to be an always-online, multiplayer experience. Oh, and should be easily monetized. New features: game store, microtransactions, over-priced DLCs, all that jazz. Raf got fed up and quit. Over 50 employees followed suit.
Arkane Austin as we knew was dead.
TL;DR: Fuck Bethesda.