Looking more at the game than hoping to predict the future:
Workers and tile improvements: gaining the ability to work in mountains, and to work the oceans. Mountains could have mines, but better would be a 'chalet' - a cottage that grows as normal, and also gives
Oceans and coastal tiles should also have cottages (Hong Kong already has a floating town, and I believe other cities do as well) or farms (as plankton farming has been suggested RW).Roads and rail lines are also theoretically practical at the moment, so should be available as future techs.
The ability to work currently useless tiles, eg tundra and desert.
To keep emancipation worthwhile, Towns should be able to grow larger: perhaps called exurbs or 'feeder cities'. In addition to increasing gold, they should also increase
and/or
Alternately, a variant on slavery/nationalism that lets you 'whip' towns.
Settlers: should eventually be able to found cities on ocean tiles.
Space: a wonder called the "powersat" - puts a solar power plant in every city you own. The option to nudge asteroids to strike at enemy nations - these would effectively be supernukes; and a random asteroid strike as a disaster so that no one is sure whether it was a deliberate attack. A wonder to blast away asteroids, both aimed and random.
A Space Corporation that gives access to metal resources (mined in the asteroid belt).
Pollution: artillery upgrade that lets the unit fire pollution at a tile. The ability for military units to Pillage pollution. A National wonder that gives a free specialist for every tile that is polluted (consider the way India has villages who live in garbage dumps, recycling everything).
Religion: Go through the options *again* - so Free religion becomes default, but can also have Organised Religion, or Theocracy, or Pacifism. Or Theocracy as default, but also Organised Religion or Pacifism.
Politically: 'semi-autonomous regions' - can build an extra Palace in city with significant foreign pop, benefits cities with that foreign element.
New Corporation: "Ecotourism" - uses up Whale (gives
and
) and Elephant, (gives
and
)can only spread in nations with Environmentalism Civic.
The ability to trade
- allowing you to dump your rubbish in the 3rd world.
UN resolutions: "Hunting preserves" animals can appear with cultural boundaries (providing easy xp), "Autonomy Vote" currently rioting city becomes a new state, "Open Source" all nations must share currently known techs; "Disband" United Nations Expires.