Wouldn't that be a bad thing though? Like obviously it's good that it would be coming to PC but then that's less of a reason for people to get an X1.
What people? What people are going to choose a Halo 5 PC vs a Halo 5 Xbone version?
The market size of PC gamers who own a PC powerful enough to play Halo 5 on it AND own an Xbone AND would opt for the PC version over the Xbone version is a pretty small market.
All they would be doing is selling more copies of their game. The people they would lose is tiny compared to that.