Over the last 40 years, network traffic has consistently grown at an exponential rate, and there is no indication this relentless trend will cease. At present, industry is hard-pressed to identify how future networks will continue to scale in capacity, energy consumption, and economic viability as present day technologies are being stretched to their limits. The nascent technology of space-domain multiplexing (SDM) for high capacity transmission is the only solution with the scaling potential to meet future demands. However, there is still a large technological chasm between the transport solution and the SDM network implementation.INSPACE proposes a novel networking approach by extending the established spectral flexibility concepts to the SDM domain and significantly simplifying the super-channel allocation and control mechanisms, by removing current limitations related with the wavelength continuity and fragmentation issues. The new concept utilises the benefits of the high capacity, next generation, few-mode/multi-core fiber infrastructures, providing also a practical short term solution, since it is directly applicable over the currently installed multi-fibre cable links. The realisation of INSPACE approach is enabled by the development of novel multi-dimensional spatial-spectral switching nodes, which are fabricated by extending the designs of the existing flexible WSS nodes, incorporating advance mode/core adapting techniques. The concept is further supported by novel processing techniques that minimise the mode/core interference as well as new network planning algorithms and control plane extensions that are enhanced with the space dimension. The INSPACE consortium forms a strong industry driven research team targeting not only the demonstration of the new network concept and its ability to meet the challenges of delivering exponentially growing content over the next twenty years, but also the full exploitation of its potential towards commercialisation.