Is there any intentions of selling Painkiller Universe instead of Black Edition?
The retail version contains a CD key that makes the game not installable in Linux* so I was wondering: the edition sold here does the same?
*http://bugs.winehq.org/show_bug.cgi?id=21295
I know it is not a Painkiller problem, I just want to know if I can play outright after buying.

The GOG version of Painkiller Black doesn't require a CD key, nor has any other copy protection. I'm not guaranteeing it will work on an unsupported OS though.
As for Universe, GOG can't comment on any deals they may have in the works. But it's not impossible that more Painkiller games could make it here in future.