Too late for that - NX is a standarad feature on x86 and has been for a long time. It is probably included in the other major architectures as well.Two problems:
1: NX on x86 has always been on a per-segment basis. The execute protection bit on pages was curiously omitted. Intel was assuming back then that everyone would be using a segmented memory model instead of a flat memory model, apparently. The existing x86 stack protection hacks exploit the per-segment protections at the expense of speed.
2: NX protection has not existed until recently on some other notable architectures, like MIPS and PowerPC.