I don't think releasing the Master Chief Collection will hurt Xbox1 sales.  Sure, there are people with both PC and xbox1, but there are lots of PC gamers that haven't played the recent Halo games.  Also, MCC are old, last gen games.  As long as they don't release Halo 5 for the PC anytime soon, I don't think it matters.

 I would argue that bringing MCC to the PC market and finding a bigger potential audience may possibly help Halo 5 and Xbox1 sales. 

I'm actually going to change my opinion on this one. 343i recently stated that the Collection would not be showing up on the 360, and said 'They had no plans for a PC version.' Which tells me timed console exclusive, since this PR speak is so easy to see through these days.

No. After Halo 2, MS realized that their number #1 IP sells Xboxs better if it stays exclusive to Xbox.

I can only imagine the fanboy fallout if Halo goes to PC. PS fans will have a field day. Xbox comes first. PC gamers are out of luck.

Also, I predict in 2015, onyl Halo 2 Anniversary will make it to 360. Not the collection.

Not sure about Halo 2, but 343 Industries already said the Halo Collection isn't coming to 360.  Predictably, though, they left the door open for a PC version by saying 'They had no plans'.

It could handled it, on like 7 CDs.

It may happen by the time Halo 5 releases. It won't be selling on xbox one anymore and might persuade some pc gamers to buy an xbox one to play the next chapter of the franchise.

Oh yeah they totally don't. Xbox one drivers, Age of Empires HD, Fable Anniversary, Rise of Nations: Extended Edition. Could they do much more? Yes, but that doesn't mean they don't give a toss about it. Also, check Ubisoft's lastest financial report, PC is their biggest platform, piracy right?

The Collection won't make it, but Halo 2 by itself? More possible id say.

343: MS, we have plans to bring the MCC to PC in the future.

MS: No, you don't.

(That's how I imagine their board room meeting going down lol)

Why the hell would they do that?

Most people who want this on PC seem like the type that only want it on there so they can keep saying "Xbone has no real exclusives! PC/WiiU/PS4 is where it's at!"

PR speak is easy to recognize these days, as all devs have pretty much adopted it.  The fact that they didn't outright deny the possibility of a PC version, is pretty much confirmation it'll come eventually.

For me yes. 3 months after xmas, it will announce, and will be released next summer.