The cybersecurity challenges in the European energy sector have significant cross-border element that needs to be reflected in the collaboration and coordination on obligations and rules applicable to the system operators. The rules for transmission system operators are developed by European Network of Transmission System Operators for Electricity (ENTSO-E). In early 2024, new transformative rule book for cross-border cybersecurity will be established through the upcoming Network Code on Cybersecurity (NCCS). In our contribution, we introduce the NCCS, procedure leading to its adoption, core concepts, main provision and likely impact. Subsequently, we discuss in detail its expected benefits and weaknesses as well as suitable future progress in line with the development of robust and resilient European energy infrastructure with regard to cybersecurity.