No, 343 continues with mainline Halo games with MC, meanwhile MS hires third party (or even first party, if they are interested) studios to create other Halo titles focused on other stories, this way we can get multiple interesting games on the Halo universe. Imagine a Halo RPG made by a third party or one of the Xbox studios, or a Halo immersive sim made by Arkane, maybe they would hire IoI to create a stealth game on the Halo universe, this is much more interesting.