According to Phil Spencer in his interview with Dropped Frames, 343 Industries will work with the Halo community to build the game after launch, just like Rare has done with Sea of Thieves.
Source: Twitch
This is going to make me sound like -Yoink-, but we knew the game was going to have a 10 year content plan a while ago. I have mixed feelings about it being so long, but the potential with this plan is INFINITE. 
Imagine them making the whole ring available throughout the years; each sector having unique environments and weather. I just think it’s going to be difficult to keep people’s attention that long; the only game I can think of that’s been successful that long is WoW. Destiny was supposed to have a 7 year plan if I’m remembering right, which I guess they’re kinda pulling off, because D2 didn’t change a whole lot, in my opinion. As long as their plan is carried out well, I think they’ll be able to pull it of.
with 10 years im sure theyll even implement some features fans have been begging to make a comeback, if they aren’t available at launch that is.
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> According to Phil Spencer in his interview with Dropped Frames, 343 Industries will work with the Halo community to build the game after launch, just like Rare has done with Sea of Thieves.
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> Source: Twitch
I’m sure they will work with the community to put in new playlists and content.