I think Xbox Studios should act as an ideation group, one which conceptualizes games they would like to see focus and offers them to whoever wants to pick them up with an associated budget, and if no internally owned studios want to pick them up look out for 2nd party partnership to realize the vision. 

With this approach, the hands-off approach of Xbox is preserved while they still prioritize projects they would like to see materialize.

I agree with most of your list except:

Smash Bros type is definitely possible however others have tried and failed to copy Nintendo's success there so maybe Xbox won't be looking at prioritizing this one.

Also, the open-world Fable might already fit the bill of a Zelda-like experience.

They have 505 on LinkedIn, so I feel like maybe he was using an older number. But let's stick with 450 for now. 250 on Starfield DLC currently, Bethesda Austin does Fallout 76 and they have roughly 100 devs. So that is 350/450 accounted for, meaning they should have at least 100 on TES 6 now. Wonder how many they had on TES 6 throughout the 5+ years between TES 6's announcement and Starfield's release? Hopefully they are at least like 20% done after working on it for the last 5+ years, would love to see it release Holiday 2028 alongside the next gen Xbox. 

They really need to staff up some more and up their game with TES 6, they're going to need to work that extra bit harder just to counteract the Xbox tax now and see TES 6 review 90+ like it will surely deserve. 

+ Fallout Next Gen Update and Mobile Games.

Yeah, what the heck is going on with that Fallout 4 update, was supposed to be a 2023 release but we haven't heard a thing about it in like a year now. Get that update out already. Would be one thing to take this long if it was a proper new gen update with noticeable graphics improvements (HQ textures, improved character models, lighting improvements, etc. like the Witcher 3 next-gen update got), but it's just 4K support for Xbox Series and PS5 and a 60 fps mode for PS5 (Xbox already had 60 fps through FPS boost, though maybe they will boost the resolution on that mode from 1080p to 1440p or something alongside the new update) and some new Creation Club content, it shouldn't take more than a year to do that. 

The expansion doing some good for AoE 4! Reached Steam's Global top 5 sellers by Revenue and number 2 best-selling game globally in general

A live performance of this needs to be the musical act for The Game Awards this year:

I just now realized thanks to a youtube video recommendation that Remedy recast Saga for Alan Wake 2. Quantum Break had an Alan Wake 2 teaser video hidden inside of it, where you can see the original Saga actress alongside her FBI partner Alex Casey, the teaser is for "Return", which is the name of Saga's campaign in Alan Wake 2:

I appreciate many of those games, and agree they are getting more diverse in their offerings. However, as fun as they are, none of them are truly kid friendly games. Hi-Fi is a wonderful game, but had some inappropriate language in it for kids. Psychonauts 2 has some non-kid friendly stuff as well, if it's anything like the first. Grounded can feel like straight horror with the spiders. Pentiment, As Dusk Falls, Age of Empire, MS Flight, and the racing games and Ori are either not kid friendly or too complicated for kids.

They have a lot of content for 10 or 12 and up, but basically nothing outside of Minecraft for under 10 years old yet can be enjoyed by adults like many of Nintendo games.

With all the many thousands of developers MS now has, I'm 100% certain thete are at least 300 who would love to make MS own Zelda action adventure game, at least 200 or so that could make a 2d Mario-like game, etc.