Hybrid Monetary Ecosystems: Integrating Stablecoins and Fiat in the Future of Currency Systems

With market capitalization exceeding USD 200 billion as of early 2025, stablecoins have evolved from a crypto-focused innovation into a vital component of the global monetary structure. This paper identifies the characteristics of stablecoins from an analytical perspective and investigates the role of stablecoins in forming hybrid monetary ecosystems where public (fiat, CBDC) and private (USDC, USDT, DAI) monies coexist. Through econometric analysis with multiple models, we find that stablecoins maintain strong peg stability, while each type also exhibits distinctive responses to market variables such as trading volume and capitalization, depending on the mechanisms behind. We introduce a hybrid system design that proposes a two-layer structure where private stablecoin issuers are backed by central bank reserves, ensuring uniformity, security, and programmability. This model merges the advantages of decentralized finance and payment innovation while utilizing the Federal Reserve's institutional trust. A case study on the 2023 SVB-USDC depeg event illustrates how such a hybrid system could prevent panic-induced instability through transparent reserves, secured liquidity, and interoperable assets. Ultimately, this research examines the model using the Dybvig model and Monte Carlo Simulation and concludes, with the results of the examinations, that a hybrid monetary model not only enhances financial inclusivity, scalability, and dollar utility in digital ecosystems but also strengthens systemic resilience, offering a credible blueprint for future digital dollar architectures.