MS has now been on consoles 19 years and owns a few IPs at this point. A good number of them dormant. Which would you like to see make a return? Yes, those from newly acquired studios do count.

I'd love to see Captain Skyhawk. Wizards and Warriors. Jet Force Gemini return from Rare.

Aside from that. I'd love to see a Lost Odyssey 2 but even more so a true Blue Dragon sequel. I have the DS  games but meh. Doesn't satisfy me. Tho I guess with a Switch port of DQXI that probably kills what little if any chance it had. Blue Dragon is a very underrated game IMO. Can't forget that Nobuo Uematsu score either. If you even have remote interest in DQ or something similar and BD is BC on XBO then give it a shot.

Freelancer.
Black and White.
Kameo.
Perfect Dark.
Banjo Kazooie.
Killer Instinct.

Funny that we disagree on the Zelda thread/games, but I agree with everything you put here. Wizards and Warriors was my first thought reading the title of the thread, love that series.

• Perfect Dark
• Crimson Skies
• Lost Odyssey
• Conker

Not sure if you can call these dead yet since they all got a release earlier this gen, but I also want to see sequels for:

• Killer Instinct
• ReCore
• Ryse
• Quantum Break
• Crackdown 3
• D4
• Crimson Dragon

Sad to say but D4 is dead. once Swery left Access Games he announced D4 is done.

The D4 situation was an odd one. He was right in the middle of developing a second season and had even released a screenshot for it, when he decided to take a sebatical from Access games for his health in  order to recover from Reactive Hypoglycemia. He was gone from Access for like a year on this sick leave, then claims they fired him because he took so long off. But then almost immediately afterward he opened White Owls and immediately started development on JJ Macfield. But considering he made Deadly Premonition 2 happen after leaving Access Games, which was an Access Games IP, D4 season 2 could also eventually happen. He even reused the D4 apartment in Deadly Premonition 2 with a few changes, which some think may have been a hint at D4 season 2. 

Both apartments are in Boston I believe. Same triple window in the living room, with a shelf and radiator directly beneath it. Same brick wall on the right side of the living room. TV in the same location (though a newer tv than the one in D4).

I think MS has co-ownership of the D4 IP with Access, so MS would need to convince Access to let Swery's White Owls studio develop it as a Series X/PC exclusive. 

Perfect dark
Conker
jet force gimini
Lost oddysy
Hydro thunder (Microsoft bought the hydro thunder series from midway)
Crimson skies
kameo
viva pinata
magatama {they own this franchise} (Microsoft Dark souls exclusive to japan xbox from 2001 I think)
Project gotham racing
scalebound I heard they still own this franchise (probably when they buy a japanese studio that japanese studio first game will be this beauty?)
Phantom dust (better one)
banjo
blast corps
True fantasy live online (same give it to a japanese studio they'll acquire in future)

Haha I remember this.. Peter Molyneux was the ultimate snake oil salesman back then. Its such a shame after he gave us classics like Black and White and Fable.

But to answer OP - Age of Mythology, Lost Odyssey and Perfect Dark.

Quantum Break. Don't really care if nothing else is brought back.