1. A hybrid virtualized distributed computing system comprising: multiple host computers, each including a hardware layer that includes one or more processors and one or more memories, and a virtualization layer that provides an execution environment for one or more virtual machines that each run a guest operating system which in turn, provides an execution environment for an operating-system-level virtualization layer that supports one or more containers, each of which provides an execution environment for one or more applications; and an elastic scheduling subsystem that monitors, for each type of guest operating system running within one or more virtual machines, utilization and allocation of a computational resource, extrapolates a future demand for the computational resource by the containers running within the execution environments pi vided by the guest operating systems of the type of guest operating system based on the utilization and allocation of the computational resource, and when the extrapolated demand exceeds a fraction of a remaining available amount of the computational resource allocated to the virtual machines running guest operating. systems of the type of guest operating system, provisions and launches one or more additional virtual machines running guest operating systems of the type of operating system to anticipate the extrapolated demand for the computational resource.