Larian has confirmed there will be a Linux release, they just have not announced an ETA. After the PC and Mac releases is that terribly surprising? In response to a tweet asking if it would be released this year, Larian responded "We certainly hope so!", which, unless you are a pessimist, implies a release well before the end of the year.
It actually implies they haven't bothered at all. Which is a shame because the windows and the linux build could almost be made together. The mac build is of course a little bit weird.
If they hope it will be this year, it will be next year, and that is a realistic stance. This game was planned for november 2013. It became juni 2014. I don't hold that against them because the original release dates were absurd. It's just how a developers mind works.
But if I compare it to another kickstarter project: wasteland 2. They really are a year late (even though they had a more realistic time table), but every engine bug is being worked out. The beta testing is on multiple platforms. Even though they use a standard unity engine, there are still platform and engine bugs to work out.
I am guessing that with an in-house made engine, these problems are way bigger to handle, especially if you adapt the engine for another platform as an afterthought.
So for my feeling, I think we can expect the first beta end 2014, start 2015. And the release will probably be Q2 2015.
That's fine with me, because I know the game will be wort the waiting. I hope the engine is too. And I do not have any time this year to play games.
If it appears sooner, I do have a major problem, because I still do not have the time :-(.