Reinventing the wheel

Weeee, speculation / theorizing time!

Civilizations that would be great to change due to the newly introduced trade mechanics:

Dutch

East India company
+30% radious to sea trade routes, +1 extra sea trade route at the arrival of renaissance => A more historically accurate UA that takes advantage of the new trade route mechanics, it would encourage the Dutch to explore in order to fully exploit it

Polder: Keept as they are on their currrent incarnation, but with a twist: polders would grant riverside status to cities built next to them (because: canals!), thus giving them all the benefits that goes with them (special buildings, trade route bonuses, etc) => Not only it would give it a good bonus to what it is an extrmely situational improvement, but it would also expand the Dutch trading capabilities and add a little twist to city placing


Arabia

UA: Trade caravans: Land trade routes yield +25% more gold, and have an increased +50% religious preassure => Since land trade routes are suppousedly going to be pretty weak compared to the seaside ones, it would be cool to have a UA that boost them, not to mention that such UA would greatly increase their utility as a religious mechanism, thus making the Arabs great at expanding their religion too as it happened in the real world!

Germany

UA: Renanian capitalism
International trade routes (recieved or emitted) provides +1 production, +2 if it comes from a riverside city => A good way to reflect Germany's industrial and economic prowess. Surely much more historically apt than the current "durrr Germanic barbarians, herp derp" one

Panzer => Keep it as it is now, but give it some extra oomph in order to compensate for its late game introduction: +1 extra attack / movement after destroying an enemy unit, this promotion will be carried over time

More to come later!

Russia:

UA: Scorched earth tactic
Enemy units gain no health or gold when pillaging improvements in Russian lands. Russian units can pillage their own improvements for 50 health. Workers spend no movement cost for repairing improvements.

UB: Krepost
Replaces Walls. Production cost of 25 instead of 75 (Standard game pace), 25% decreased tile culture & gold cost. Allows for two units to be garrisoned in the city.

UU: Cossack:
Same as usual.

I think the new UA is more appropriate for Russia, since it is known in history for being unconquerable due to its earth-scorching tactic (and weather, but that can't be replicated in this game). The Krepost wasn't very interesting to begin with, so I made it have a truly unique ability, that nothing in the game can be compared to so far. I actually think it should apply to regular Walls as well, but let's stay realistic here.
The low production cost makes it easy to build in newly founded cities, to reflect the Kreposts' real historical purpose, and finally, the UU should stay the same. The Cossack is not a great unit, but I can't figure out a way to improve it, so I'll just leave it like this.

A nice idea for a Spain makeover.

Spain

UA: reconquista When taking over a city, convert 50% of the population to the religion you already follow. Gain 25 for each person converted this way. (SO if you converted 10 people, you would gain 250 faith)

UU: Conquistador Replaces the Knight. Gains equal to 1.5x that units . 15% more expensive to make or buy then normal Knight. 23 instead of the normal 20 and 1 movement.

UU: Spanish Galleon Replaces the Frigate. Gains equal to units when that unit is killed. 165 cost. Has 30 . Starts with the targeting 1 promo.

Reasons.

Honestly, I'm disappointed that the OP didn't give France's Dragoons the ability to leap directly to any tile within a three-tile range.