Probably exclusive in the console realm to Xbox One until it's out of early access, similar to Ark.
I don't get why people are surprised by ambiguous wording with these deals. It benefits MS to be vague. If they say "exclusive to Xbox until June 2018" then anyone who might have gotten the game on Xbox One or even gotten an Xbox One for the game know exactly how long they have to wait. Lots of angry people in GAF... like, why? Who gives a shame.
It didn't benefit Microsoft when they tried with Tomb Raider, on the contrary, it just made them look more "evil" (I can't think of a better word) and brought ill will and malice from the community of gamers.