Good news everyone, it looks like the SteamDB info from before might actually be true about Warhammer 40,000: Dawn of War II coming to Linux. The latest information points to it being from Feral Interactive.
I was notified about this in our IRC today (thanks mirv):
rootoverrides/0/addpath: Feral Interactive/Dawn of War 2/VFS/User/AppData/Roaming
You may now begin throwing your money at your screen (please don't buy it yet). Disclaimer as always: SteamDB is by no means official or actual confirmation, but good supporting evidence.
I have reached out to Feral Interactive for comments.
I hope it's true, as it's yet another title that would excite me as an RTS fan.