This document examines the technological foundation supporting the SUSTAIN-6G project’s Use Cases and highlights the gap between their requirements and the current state of networking solutions, accounting for both technological advancements and real-world deployments.Thereto, the requirements of each individual Use Case are analysed. Based on this assessment, and the technology deployment gap, UCs are classified into one of four categories, using as a criterion the extent to which the technology gap could be addressed by an adequate deployment of the current technology, or whether novel 6G technologies offer an opportunity to address the gap either within the scope of the work on sustainable 6G technology in SUSTAIN-6G or beyond. The link to ongoing and planned project activities is discussed, clarifying the connection to sustainability criteria and their associated metrics in the context of sustainability needs and requirements, and to the planned work on proof-of-concept validation.