I just started reading about Litecoin's Scrypt algorithm and all the explanations are quite complex. I have understood that Scrypt uses more memory than Bitcoin's SHA-256 which makes it ASIC-resistant and prevents centralization.
But, from what I understand we still require powerful GPUs to mine Litecoins because operations on larger data sets (more memory) will be faster and more efficient in GPU than in CPU.
Also, why is it not possible to build an ASIC machine for Scrypt. Is it due to the complexity involved in the algorithm? I just want to know if it's impossible or just difficult. In the future, can we expect ASIC machines for Scrypt as well?