What would be useful would be a model form for players to fill out on their preferences and expectations for a D&D campaign followed by a series of suggestions about how to create a campaign that will align with players' preferences and expectations. Perhaps going further in depth with a complete example of campaign creation and play.
A new DMG MUST include lots of advice for online play. I only play in person these days, but even I recognize online play is a major segment, if not majority, of D&D play these days.