I liked the main analogy at the beggining, when explaining the main concepts: building the bank should be like building a house. The core, the design, is the walls, the irons and the infraestructure upon which the house is built. This is analogous to the technology on which the enterprise is built (should be cloud, not legacy systems!). Once this is set, the next layer, the arquitecture, the look and feel, the floor materials, or how the one living in the house perceives it, is separate. Once the bases are built, one can choose the type of house you want (open, closed, big windows, more cousy, etc.). For the bank, this means that on top of that technological infraestructure, the business decides the kind of bank: massive, only digital, premium but supported with branches (only as a sales channel!), etc. This is done by connecting the bank, and setting all of the services via APIs, which can be connected to whatever other service is requiered (Amazon, payments, apps, intelligent cars, voice assistants from any platform, etc.). The core should be able to connect with anything; to what it gets connected, is the business decision depending on the kind of bank and services one wants.