In emerging scenarios such as the Internet of Things and space-and-ground integrated networks, diverse new applications bring multi-di-mensional quality of service (QoS) requirements to space information networks (SINs). As a mixed problem of routing, traffic control, and resource allocation, QoS provisioning is concentrated on providing customized QoS guarantee to SIN users. On the other hand, motivated by the recent progress in technologies such as software-defined networking and machine learning, many potential solutions for QoS provisioning have been proposed. To utilize the state-of-the-art approaches within QoS provisioning, we provide a forward-looking vision of QoS provisioning that outlines the applications, challenges, architectures, and associated solutions. In this article, we first introduce the applications in three emerging scenarios in terms of traffic characteristics and QoS requirements and identify the accompanying technical challenges for SINs. Then a QoS provisioning architecture with two differentiated transmission modes is proposed. The mirror source mode for bandwidth-tolerant flows improves the network efficiency by centralized traffic scheduling. The preemptive mode for bandwidth-sensitive flows reduces the end-to-end delay by edge node control. Furthermore, the enabling technologies and potential solutions for control logic and forwarding mechanism are analyzed. At last, future research directions are discussed.