I mainly just wanted to say the idea of a Banking DLC has been on my mind a lot playing capitalism lab. I may have even suggested it a few times (also the Utilities and Freight DLC would be amazing)
So I am not an expert at banking by any means, and this is a really watered down version of how I see the finance industry.
I think the DLC should feature different tiers of 'Loan contracts', and answer the grand old question of "Where does money come from?"
1st - National Government - A national government can provide the largest and lowest interest loans.
The National Govt has the lowest risk associated with their loans because they control the money supply, and ability to seize assets.
National Governments would loan money to Cities and National Banks
(You could also have other nations with lots of extra money/GDP to offer even better loans to banks in your country, making it more competitive)
2nd - City Government & National Banks - These 2nd tier money distributors would not take on the risk of loaning to everyone
City governments and National banks would provide large loans at competitive interest rates to smaller private banks and offer corporate loans
3rd Regional banks - These banks would function as a financial service provider. They would offer a savings platform to generate lower interest loans if their customer base is particularly wealthy.
They would take on higher risk and higher reward. Perhaps a higher banking tech rating would reduce the number of loans defaulted on
Regional or City banks would offer loans to local industry (NPC MOM & POP SHOPS, CAR LOANS, HOME LOANS, ECT)
A lot of the banks I invest in (in RL) are not even technically banks. One company for example: Manhattan Bridge Capital (Ticker:LOAN) specializes in providing loans under 1 year for repairs or upgrades that wouldn't take over a year to do.
In business a newer strategy I see taking over at corporate levels is collective bargaining. Corporations are hiring 3rd parties for everything these days, because it is a lot more profitable to say.... Hire a company that specializes in.. Freight, Human Resources, Purchasing, Inventory, ect ect. This banking DLC might touch on the ability to take on risks companies typically had to take on themselves.