Soon, MS will make all Halo games part of the Backwards Compatibility library. ArsTechnica thinks this spells doom for the Master Chief Collection, but I think it was already doomed.
https://arstechnica.com/gaming/2017/07/halo-backwards-compat-news-may-spell-death-knell-for-master-chief-collection/

Update, 2:47pm ET: 343 Industries responded to our H:MCC questions about possible 4K patches and matchmaking bug-fix patches by sending this statement:

We’ve made a host of significant improvements to Halo: The Master Chief Collection since the initial launch in 2014, and while the majority of players enjoy the game regularly, any issues or interruption in play is something we continue to keep a close eye on. That said, we do not have any additional updates planned in the near term, at this moment.

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More importantly to me than the MCC that I stil have not played after buying, does this mean I can use all my carefully refined rocket race maps and rulesets? Are they still stuck on my 360’s HDD?

More importantly to me than the MCC that I stil have not played after buying, does this mean I can use all my carefully refined rocket race maps and rulesets? Are they still stuck on my 360’s HDD?

If they are stored in your Xbox 360 Cloud Storage then you can access them on your Xbox One. If they aren't already there you'll have to copy them over to Cloud Storage first.

If it works like Reach, you have to upload them to Cloud storage, and then the version on the One will pick them up. The tricky part is that copying to the Cloud can be time consuming and fiddly if you have a lot of saved games and films, since the 360 storage menu lumps them together.

This will make organizing LAN parties for the youths so much easier! Yay!

Soon, MS will make all Halo games part of the Backwards Compatibility library. ArsTechnica thinks this spells doom for the Master Chief Collection, but I think it was already doomed.
https://arstechnica.com/gaming/2017/07/halo-backwards-compat-news-may-spell-death-knell-for-master-chief-collection/

This is good news, I liked MCC better than most. Of course I bought it primarily for the campaigns, not the multiplayer. About matchmaking times, that may be solely dependent on the size of the player pool at this point.

It'll be interesting to see whether they make Halo: CE and Halo 2 backwards compatible.

Soon, MS will make all Halo games part of the Backwards Compatibility library. ArsTechnica thinks this spells doom for the Master Chief Collection, but I think it was already doomed.
https://arstechnica.com/gaming/2017/07/halo-backwards-compat-news-may-spell-death-knell-for-master-chief-collection/

This is good news, I liked MCC better than most. Of course I bought it primarily for the campaigns, not the multiplayer. About matchmaking times, that may be solely dependent on the size of the player pool at this point.

It'll be interesting to see whether they make Halo: CE and Halo 2 backwards compatible.

You have to assume they're coming with the OXbox BC program.