I'm not really sure why this matters... People still bought an Xbox One for Titanfall, despite it being cross released at the same time on PC... At the end of the day it's more exposure on the market for the game and opens it up to two platforms. More software sales isn't really a bad thing, considering that's where the money's made.
I'm not really convinced that the majority of people who would buy an Xbox One for X or Y game would suddenly reconsider because it's on PC too, unless of course they had a proper gaming rig to run the game on, which I would find unlikely for the majority out there.. If not, it's far more likely that they would still buy the Xbox One for the game(s), as opposed to the second option of making a more costly investment in a gaming PC.
Current gaming platforms - Switch, PlayStation 4, Xbox One, Wii U, New 3DS, PC