Gojko Adzic – Eric Evans: Why do efforts to replace legacy systems fail?:

"Starting from a proposition that “not all of a large system will be well designed”, Evans suggested identifying and focusing on the core domain – a very small piece of software that actually makes the system really worth writing, something that brings direct competitive advantage to the business. These are most likely those new and really exciting features that people plan to do after the functionality of the legacy system was fully replaced."