[sterna]

If you have a bounded system growth will eventually level out. Physical considerations makes it unfavorable to go below the atomic level for feature size. Therefore growth in transistors per area is bounded and Mores law will eventually stop being true and therefore it is nothing but a phenomenelogical law.

I think Kurtzweil has suggested going into 3D for CPU design with multiple layers of circuits, but I have seen no serious attempts to realize this so it is a bit of a long shot to depend on to keep the pace of growth intact. However, it still does not resolve the fundamental limitation of Moores law, it only extends it for some time.

[mistercow]

There has been some progress in 3D CPU design. Ivy Bridge, for example, uses a 3D transistor design although the CPU itself is still flat.