It looks like
Arkane's next project will fall out of our coverage with
The Crossing just revealed. There's little information at present but the graphic at Arkane's site says "Fusing Single Player with MultiPlayer" and a sneak preview in
Episode 60 of The 1Up Show apparently refers to it as a "crossplayer FPS" — you'll have to download the 519Mb video file to find out for yourself.
More information.