The addiction of trade routes management, with Caravans and Sea Cargo, is very recent, but there are a lot of room to expand it, either in mods for Civ5 or for Civ6 . Some things I'd like to see:
New Technologies:
New Buildings:
New National Wonders:
There should be a lot of tweaking and overall balancing in the game, in order to add the things above .
New Technologies:
- Glassblowing: Requires Pottery . Allows your cities to build a Glass Facility
- Unit Standardization: Requires Steam power and Leads to Replaceable parts . Allows your cities to build a National Measurament Office;
- Package Standardization: Requires Unit Standardization. Allows your cities to build a Packaging Facility, which increases the range of trade routes . Also increases the healing rate of units within cities connected to the capital by +5 HP/turn;
New Buildings:
- Glass Facility: Requires Glassblowing . Each Source of Citrus, Salt, Dyes and Wine generates +1
;
- Packaging Facility: Requires Caravansaries . Land Trade Routes originated from this city have +25% increase in range . After researching Plastics, Land and Sea Trade Routes generates +3 when connecting to another civilization . After Researching Refrigeration, increases the
from internal trade routes to +3 . After Researching Combustion, increases the 
from internal trade routes to +3
New National Wonders:
- National Measurement Office: Requires National College, Circus Maximus, East Indian Company, Oxford University, Ironworks and Hermitage . Increases the yield from all specialists by +1, increases the yield of buildings that produces or by 1, and increases the
from international trade routes that you sent to other civilizations and to international trade routes other civilizations sent to you
c5science: value increases for both sides)
There should be a lot of tweaking and overall balancing in the game, in order to add the things above .
