Future high-end computers which promise very high performance require sophisticated program execution models and languages in order to deal with very high latencies across the memory hierarchy and to exploit massive parallelism. This paper presents our progress in an ongoing research toward this goal. Specifically we develop a suitable program execution model, a high-level programming notation which shields the application developer from the complexities of the architecture, and a compiler and runtime system based on the underlying models. In particular, we propose fine-grain multithreading and thread percolation as key components of our program execution model. We investigate implementing these models and systems on novel architectures such as the HTMT architecture and IBM's Blue Gene. Also, we report early performance prediction of thread percolation and its impact on execution time.