Quantic Dream's Beyond: Two Souls has also reached million-seller status--much like its predecessor, Heavy Rain. According to the developer, the game reached the milestone "shortly before Christmas 2013."
Although the game was not as well-received, it featured the work of Academy Award-nominated actress Ellen Page as the lead. The game also showcased at the Tribeca Film Festival.
Given that Quantic Dream's games end up being technical showcases for Sony, it's unsurprising that the developer is already working on a new PS4 project. The fact that these games end up being profitable for the publisher probably doesn't hurt either.