The motivation for this paper comes from the recognition that our understanding of specialisation might be too simplistic and that the dichotomy of specialisation and diversification could be outdated not reflecting the richness of real complex economic and technological relations among industries. Drawing on a qualitative study of the Hamburg Aviation (HAv) cluster, this paper discusses the peculiarities of a cluster profile in the digital time – the age of Industry 4.0 (I4.0), touching upon the issues of cluster structure and the complexity of production, synchronising specialisation with diversification, branching, and bridging, and the I4.0 attributes facilitating complementarity. The final research proposal, which is empirically embedded in the studied context, states that related variety encompassing both ‘specialisation in diversification’ and ‘diversification within specialisation’ can be further developed by a blending process. This can lead to branching and is modulated by the universal character of the I4.0 and a problem-solving attitude. It takes the form of an additive (new entries) or multiplicative (spinoffs) evolution, and, ultimately, owing to the complementarity, it can provide sustainable competitive advantages.