The next generation air transportation system (NextGen) implementation plan (NGIP) describes the system changes and operational improvements that need to be implemented through the mid-term (2012-2018) to realize NextGen. It is anticipated that the system wide information management (SWIM) program will provide functionality that will help the Federal Aviation Administration (FAA) achieve the goal of a network-enabled National Airspace System (NAS) expounded by NextGen. This paper summarizes the possible evolution of SWIM functionality/operations in the mid-term to support the capabilities contained in the NextGen solution sets, such as trajectory based operations (TBO) and reduced weather impact (RWI), which require net-centric services. Our preliminary analysis indicates that a hybrid approach to the implementation and operation of SWIM functionality is a strong candidate to support mid-term needs. In this approach, services are allocated on a case-by-case basis to be implemented and operated in a consolidated "core," or to be implemented and operated within domain-specific NAS systems. At this point, the mid-term NAS services have not been identified and allocated for deployment to individual NAS systems or to the SWIM core. Our preliminary analysis indicates that SWIM, in the mid-term, should include some services that are allocated to a consolidated SWIM core. These services should be selected to reduce cost and risk, maximize benefit, and provide a basis for building on success in subsequent segments.