Security is a major concern in all computing environments. One way to achieve security is to deploy a secure operating system (OS). A trusted OS can actually secure all the resources and can resist the vulnerabilities and attacks effectively. In this paper, our contribution is twofold. Firstly, we critically analyze the host vulnerabilities in modern desktop OSs. We group existing approaches and provide an easy and concise view of different security models adapted by most widely used OSs. The comparison of several OSs regarding structure, architecture, mode of working, and security models also form part of the paper. Secondly, we use the current usage statistics for Windows, Linux, and MAC OSs and predict their future. Our forecast will help the designers, developers and users of the different OSs to prepare for the upcoming years accordingly.