Is there a final version of the work of an Islamic bank in the system consists of a purely riba-based banks?

Off course, there are two attempts in Iran and Sudan to run a pure Islamic banking system. However, almost all of the existing Islamic Banks today are working in alongside with the conventional. These banks are either fully fledged Islamic bank or subsidiary or a window of conventional bank. It is easy to differentiate the operation of the fully fledged ones. Whereas, the windows one need a special treatment with regards to pool of fund, system requirements, accounting... etc. This is necessary because there are many shared services between the Islamic windows/subsidiary conventional bank.