Managing resources by amount, and not by access.

If I remember correctly, in Endless Legend, you have amounts of resources. I think that would be a great idea.

If I have 500kg of salt in my principal city, I still have that resources even if have lost the access to salt. Salt, aluminium, horses, mercury, gold, silver... That would restructures Diplomacy, Units Creation and Trade System.

Also, you could build a new district named Warehouse or something like that, where you can have a limited amount of resources. If you want more, you can build another warehouse dristict, or you can sell it by amount, an amount you offer as you are the seller. (And by selling i dont mean just gold. You could ask for others resources, access to other resources [yes, the access its a great idea, it shouldnt be deleted, just revalue having access to them]) and not just simply sell it by the amount the game wants.

Even you could manage fuel in naval units or in cities and poblation.
What if a city works loww in production because in the contemporary age you have 0 oil and you havent reaserched electrics motors? What if your city could run with only electricity or nuclear energy unlocking new researchs? I dont know, just ideas.

The principal problems I see with the actual system, is:

You can't choose the price. It's just the amount of transport and abit of gold each round.
6 Civs could extract Gold from an infinite access.
Its has 0 beneficies (apart of the passive beneficies) having acces to X resource.

The principal ideas that could be implanted and would improve the Diplomacy, Units Creation and Trade System:

Global Market. In a global market, where you have ALL the oil access of the world (Like Arabics zones or Venezuela) you actually have something very precious. Something that could be payed with highs amounts.
It could improve the way the trades and diplomacy exist. Actually, you just sell X access to some random and have 35g extra each round, for example. But with this new trade system, (new = I remember having played in Endless Legend, idk if it was exactly like this, but yeah) you could exchange traties, other resources, money, religions, declaring wars...
New researches where you have to develop new technologys to the resource you are extracting. I dont think it would be totally fair if 6 civs are extracting from the same resources, everyone would extract the same amount. Miner civis exists.
Improving creating new units. It would be more fair if to create a unit, you need 50Iron, for example, an not just create what ever you need. Because you are telling me, you need 2 iron access to create a Moder Ship and a Elephant with a cannon? Idk

I hope i have explained my self. It's not my first language, so I'm sorry.

Ah, and it would be great too, if this would be free base content xdd