A new digital back-end architecture for the Very Long Baseline Array (VLBA) is being developed at NRAO. The system will consist of several main components that are interconnected through a 100 Gbps Ethernet switch. A pair of dual-channel IF samplers will be placed in the VLBA receiver cabin, producing four VDIF streams at 2048 Gsps and with greater than 8 bits per sample quanitzation. These "digital IFs" are to be injected into the 100 Gbps switch as VDIF packets over multicast UDP, allowing one or more "consumer" modules to perform further processing. For the VLBI use case, a module that channelizes and requantizes the data will feed Mark6 recorders. the architecture will allow other commensal uses of the digital IF streams such as transient searching, pulsar timing, or spectroscopy. In this talk, I will discuss the overall system architecture, the status of the project, and the motivations that led to this particular design choice.