It's official! From Activision today:
“Call of Duty: Modern Warfare Remastered boasts vibrant current generation visuals, with fully improved texture resolution and detail, high-dynamic range lighting, lit and shadowing VFX particles, revamped animation and audio, stunning sound, and much more. Fans will relive the full, iconic campaign as they’re transported around the globe with Capt. Price, Gaz and Soap across all the missions from the original game, including ‘All Ghillied Up,’ ‘Charlie Don’t Surf,’ and ‘Crew Expendable.’
“Players will also experience the online multiplayer mode that redefined Call of Duty by introducing killstreaks, XP, Prestige and more, and battle head-to-head in 10 fan-favorite maps from the original multiplayer mode, including classics such as Crash,’ ‘Backlot’ and ‘Crossfire.'”
Call of Duty: Modern Warfare Remastered will be included with the following editions of Call of Duty: Infinite Warfare:
- Legacy Edition and Digital Legacy Edition – Includes both Call of Duty: Infinite Warfare and Call of Duty: Modern Warfare Remastered ($79.99/89,99 €

- Digital Deluxe Edition – Includes Call of Duty: Infinite Warfare, Call of Duty: Modern Warfare Remastered and Season Pass ($99.99/109,99 €

- Legacy Pro Edition – Includes Call of Duty: Infinite Warfare, Call of Duty: Modern Warfare Remastered, Season Pass, collectible Steelbook, official game soundtrack and additional digital items ($119.99/119,99 €

No news yet on whether you’ll be able to pick up Modern Warfare Remastered separately.
Not mentioned in this but Raven is the developer working on this