It’s been announced today that Halo 5: Guardians will be going 4K, and Halo 3, ODST, 4, and Anniversary are going Backward Compatible with all DLC for free. The official Xbox News Wire posted the following:

Halo 3, Halo 3: ODST, Halo 4, and Halo: CE Anniversary! Each of these games will support campaign, multiplayer and LAN play on Xbox One – including LAN play between Xbox One and Xbox 360! Once these titles are added to the program, you’ll be able to pop in your original disc or purchase a digital copy of the game via the Xbox Store and jump right in. Additionally, every Xbox 360 Halo add-on map pack in the Xbox Store will be made available for free, ensuring you have everything you need to achieve maximum enjoyment in online matchmaking or custom games.

It was also announced that Halo 5: Guardians will receive a game update to support true 4K with the release of Xbox One X later this year. As for Halo Wars 2, once the Season Pass wraps up in August, Halo Wars 2 fans will want to set their sights on this Fall’s new premium expansion, “Awakening the Nightmare,” which includes a new campaign from the perspective of The Banished, the return of an ancient and deadly foe in the Flood, two new Banished Leaders, and a brand-new multiplayer game mode “Terminus Firefight.”

Source: http://xboxtavern.com/halo-5-going-4k-plus-backwards-compatibility-free-dlc/

I am wondering if the 4k update meens a PC release but no info yet on that

So, will they be equivalent to the Master Chief Collection versions? Or are they going to look different?

Pretty sure the MCC also just has the xbox360 games that are run on a version of the emulator so they should look at least the same, but ODST wasn't included and its always nice that people who don't have the MCC but do own the games can play them!

I thought they added ODST to the MCC with an update? Or was that just for a limited time?

Limited time only, so any new buyers of the One X will surely have missed out on this (like me)

"Halo 3: ODST is being offered for free, via download code, to Xbox One owners who played Halo: The Master Chief Collection from its Nov. 11 release date until Dec. 19; it's a make-good for the pervasive problems the shooter faced in its online multiplayer for several weeks after its release."

Can't wait for Halo 5 to be a 1 TB install

It was free for those who had trouble with the multiplayer back then but it's available to buy for $5 as a DLC.

https://www.microsoft.com/en-US/store/p/xbox-now/bz8p16vh1gzp

No they are still enhanced on the MCC. The 360 Halo are 720p or lower running at 30FPS, while the Halo games on the MCC run at 1080p 60FPS.