In this paper, we propose HybridCoin, a next-generation cryptocurrency that combines the advantages of both Bitcoin and Ethereum to create a highly versatile and efficient digital asset. The goal of HybridCoin is to unite Bitcoin's proven store of value and robust security features with Ethereum's powerful programmability and smart contract capabilities, thereby enabling a wide range of use cases and applications. We present the design and architecture of HybridCoin, with a focus on the consensus mechanism, scalability solutions, and smart contract functionality. We also discuss the security and privacy features of the proposed cryptocurrency, along with its potential use cases in digital payments, decentralized finance (DeFi), and asset management. Furthermore, we address the environmental sustainability and energy efficiency aspects of HybridCoin, offering strategies for sustainable blockchain operations. Finally, we explore the regulatory landscape and potential challenges faced by HybridCoin, including the impact of emerging trends, technological innovations, and the rise of Central Bank Digital Currencies (CBDCs). By integrating the strengths of both Bitcoin and Ethereum, HybridCoin has the potential to revolutionize the cryptocurrency ecosystem and reshape the future of digital finance.