I can’t say the same about co-op as i’m pretty disappointed by that still. I did some reading around and came to the realization that the Project Spark team was brought in to assist with Halo Infinites forge.
Project spark released October 7th, 2014 and I believe it was shut down in 2018. For those of you who don’t know what Project Spark was it was an ultimate creation tool that gave players the ability to create their own worlds to be played in. When it first released it gave players a healthy amount of options to detail their worlds, fill it with terrain, objects, and even some AI. I believe there was also tools that allowed AI scripting. In it’s earlier days I remember browsing through the file share and seeing recreations of classic games like Zelda and even saw someone create a Star Wars scenario.
Here is a video on the (96) Project Spark Tutorial: Create Mode - YouTube
There hasn’t really been too much to go on regarding news on Halo: Infinite but after coming to the realization the Project Spark team had gone to assist 343 with Halo: Infinite it gives me some hope on what the new forge might be like.
EDIT: Link is broken so im gonna try and post the video here https://www.youtube.com/watch?v=verAntF4Cyo