For any given application, there is an optimal throughput point in the space of per-processor performance and the number of such processors given to that application. However, due to thermal, yield, and other constraints, not all of these optimal points can plausibly be constructed with a given technology. In this paper, we look at how emerging steep slope devices, 3D circuit integration, and trends in process technology scaling will combine to shift the boundaries of both attainable performance, and the optimal set of technologies to employ to achieve it. We propose a heterogeneous-technology 3D architecture capable of operating efficiently at an expanded number of points in this larger design space and devise a heterogeneity and thermal aware scheduling algorithm to exploit its potential. Our heterogeneous mapping techniques are capable of producing speedups ranging from 17% for a high end server workloads running at around 90°C to over 160% for embedded systems running below 60°C.