Cyber-Physical Production Systems (CPPS) enable Smart Production by linking physical processes with digital systems across the entire value chain. For a holistic integration both a vertical integration of production processes and a horizontal integration across Enterprise Information Systems (EIS) is necessary, which makes CPPS complex systems with a large number of constituents and connections. The goal is a flexible and intelligent production system based on a decentralized architecture that connects the entire value chain. Literature provides generalized reference architecture models, such as RAMI 4.0 or 5C, and a variety of specific architectures, that have mainly been implemented in academic environment. There is a lack of examples and guidelines on how to integrate the proposed generic high-level architectures and to achieve truly decentralized ones, which results in a scarcity in actual implementations of CPPS in reality. Historically, automation systems are based on the hierarchical ISA-95 automation pyramid with an intentional separation of layers, and the step for industrial companies towards decentralized CPPS architectures is large and full of uncertainties. This paper investigates actual reasons that impede industrial companies in adopting decentralized CPPS architectures. A case study assesses the situation in a large global manufacturing company based in Sweden by following ongoing activities towards a flexible and end-to-end connected production system. Findings concern the integration of ERP and PLM systems with the production system, architectural and technological constraints, and structural and organizational aspects.