For me the big miss will be attrition. Even if we get seasonal variation its hard to work attrition in with only 1 turn per year.
While not a massive game breaker I liked the extra challenge it offered. As mentioned above we can’t really tell the impact until we see the new campaign in action, even with a few existing features missing it could still work out a lot better. Maybe we’ll get terrain based attrition instead, i.e when crossing mountains or deserts.