I really think too that the Halo 5 multiplayer should not be switched to a new one with Halo 6. For the first time in ages there is a really strong and dedicated player base and the game is also 100% valid in high levels of competitive play. To throw that away in favor of a new iteration would not only be a waste, it would be risky.
Halo 6 should have a huge, awesome campaign and a ton of new content to the existing multiplayer in the form of an expansion pack. (Of course that creates, too, some conflict with the philosophy of keeping all content that influences playlists free.) If Halo 6 were to come to Scorpio, then it should only differ in terms of graphics. And if the Xbox One version of Halo 6 had better graphics (and they'd want to update the MP graphics too), it should be done in the way of a massive update to the multiplayer component.
I don't know if some of this is a pipe dream, but the main point is that the existing Halo 5 MP and its community should be preserved, and one should not introduce anything that would divide the player base.