Telecommunication networks are undergoing a significant shift from closed and proprietary systems towards open and interoperable networks. This transition allows for greater flexibility and reduced dependence on single providers. However, this openness also raises substantial security and trust issues, necessitating new approaches like the use of an intelligent and autonomous 6G network slicing security manager to manage security in multi-provider environments. Additionally, trust management is becoming increasingly crucial, with technologies such as Blockchain proposed to ensure the reliability and integrity of operations across this new, decentralized landscape. This model supports a dynamic marketplace where providers can freely negotiate and manage resources, thereby enhancing service delivery and network management.