Seems it won't support triple-wide, same as the first game.
Not sure if this being in the game's readme file as a video issue is an indication that they'd like to change that in the future.
From the game's readme
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2.2 VIDEO ISSUES
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A. Latest video drivers required. Steam provides a link for
updating video drivers in their menus if needed.
B. Mid-range NVIDIA® GeForce® 9xxx cards, such as the NVIDIA®
GeForce® 9400 GT may experience low framerate during gameplay.
NVIDIA® GeForce® 88XX or 98XX 320 MB graphics cards or higher
are recommended.
C. Some Mid-range ATI Radeon™ cards with 80 shader processors
such as the ATI Radeon™ HD 4350 & 5450 may experience low
framerate during gameplay.
D. If visual effects are seen displaying through walls with
use of an NVIDIA® GeForce® graphics card, update video
drivers to resolve the issue.
E. If screen tearing is occurring, turn on v-sync in the
video options menu.
F. Eyefinity is not supported.
Downloading on steam now, will report back when I can actually get in the game.