And all Alt Coin advances are incremental by nature.

You can only achieve some degree of "GPU resistance"...
Without taking drastic, undemocratic measures like saying...
"Must be run on 64-bit with 16 GB RAM", etc.

So if the coin requires 32 KB inner Scrypt, then HD 7970 is going to be at the 0.25 to 0.5 TB/s of the GDDR RAM but with much latency and only 4 threads so much slower than the CPU. Even if the coin requires only 16 KB inner Scrypt or later version of the GPU has 32 KB L1 cache, the GPU is still going to be employing only 4 threads same as for the CPU, but may run at twice the speed of the CPU because of the double L1 cache speed.

...

My other idea is to force the total memory requirement of the outer Scrypt higher than any GPU, since I know of no GPU which allows addon GDDR memory. There is no retail market for GDDR memory.

The idea for nested scrypt is to keep the duty-cycle of memory-bound to L1 cache near to 100% and it also provides the flexibility to control the duty-cycle of the main memory, i.e. 100% - percentage of the time that the algorithm is memory-bound in L1 cache while not writing out to the main memory. Lowering the latter duty-cycle will increase the execution-time of the hash, yet also lower the individual and society-wide electricity requirements of the coin, because for the same hardware less electricity is consumed.

Without taking drastic, undemocratic measures like saying...
"Must be run on 64-bit with 16 GB RAM", etc.