It could mean many other things, possibly more than a single one.
- More focus on countries outside of Europe, with possibly several civ for a single modern day country (China, South East Asia, Africa, the Americas…)
- More regional units, possibly with UU turned into regional units (Boyars would be one of the main candidates)
- Older civs getting their UU replaced (see above) and getting a new campaign as the old one is given to a new civ (Dracula being the main candidate, which as mentioned would be even likelier with Boyars being turned into a regional unit)
- Civs with up to 3 UU (no specific idea…)
And obviously, what you listed could also work instead of or alongside all of those.