Dealing with legacy systems is a decade old industry challenge. The pressure to efficiently modernise legacy both to meet new business requirements and to mitigate inherent risks is ever growing. Our experience shows a lack of collaboration between researchers and practitioners inhibiting innovation in the field. To facilitate communication between academia and industry and as a byproduct to obtain an up to date picture of the state of affairs we are creating a legacy system migration topology based on generalisations from a multi-case study as well as extensive literature research. We expect the topology to be useful in connecting industry needs and challenges with current and potential future research and to improve bidirectional accessibility.