Among the things that could be done very differently in Civ VII are the things that people have been discussing in this Forum's Threads for Years, and things already being 'shown off' in the new historical 4X game Humankind:
From the Forums:
1. A Resource, Research, Development scheme that allows a 'Civ' to start and play for part of the game as Pastoral or Nomadic without being so penalized that it is suicidal. We've discussed this at length, but there is new urgency in the research that now shows massive population and culture shifts since the Neolithic all the way down to the Renaissance: "Migration Theory" that was discredited for most of the 20th century is now back in full force, backed by DNA and physical archeological sources, and the Civ Franchise utterly ignores it. The 'classic' Civ model of City-Only Advancement is now a recipe for a Fantasy game, not Historical.
2. A more dynamic model for Resources in general: Civ VI started the move towards 'manufactured' or artificial resources later in the game (mostly tied to Great People): this needs to expand, and the variability of resource use needs to expand, and the substitution of one resource for another needs to be included in the game: This alone would make a dramatic change in the game play from the mid-game on, as you would have to keep developing or substituting resources to stay in the game, the way the technological advance of the Haber Process allowed 'niter' to be manufactured in any quantity desired, or converting from coal to oil-fired boilers made Coal irrelevant as a resource for navies. . .
3. A greater variety of Civilization types. Nomadic/Pastoral is a big one, but there has to be a better model for the City State or Multiple Government type of state, which includes such all-time Civ Favorites as Classical Greece and almost every other culture at one time or the other.
From Humankind.
1. A better-looking map, including more variety of landforms, better handling of elevation (as mentioned in the earlier Post here) and, I would add, more variation in the map during the game. I just finished reading an archeological report on the finding of a Sea Wall made of stone protecting a neolithic village from the rising Mediterranean - built around 2000 BCE, so in game terms, Climate/Terrain Change happens throughout the game, not just in the last Era or two.
2. Better handling of Cultural change/diversity. Humankind seems to be trying for a Progressive Culture mechanism which may or may not work well (I don't think we have enough information to be sure yet, but I, for one, am dubious). There has to be something better than putting a culture like Egypt or China that covers several thousand years into a strait-jacket with 1 - 2 Leaders and a single set of Culture traits.
3. Better handling of military action. 1UPT gives a nice tactical feel to the battles, but it is grossly out of scale with the rest of the map, the AI has not been able to handle it in two game renditions now (Civ V and Civ VI). Humankind is using the Endless Legend style of turning the game map into a temporary Tactical Map, apparently. This, at least, is something different from the interminable Civ debate over 1UPT versus Stack of Doom that we've been locked in since Civ V. Whatever it winds up being, it is time to try something new for Battles in Civ VII.