RAM requirements. I have talked about this with some people, theoretically it is possible to fit an FPGA with additional DDR3 or GDDR5 ram and have it specifically designed to mine litecoin.

The main problem would be adoption (price) and that to get ridiculous rates of hashign power, you would need ridiculous amounts of RAM.

I believe this to be a good thing. Even if ASIC or FPGA mining for Scrypt Algorhithms are designed, thanks to the RAM requirements the increase in hashing power will be less dramatic than 60gh/s avalons.

Some people argued that every 7970 in their systems adds 1.5gb ram in usage on their systems. Considering that, the average 7970 comes with 3gb VRAM. Let us take 4gb RAM necessary for 700kh/s peak power output. A 5mh/s FPGA or ASIC design would have to come with around 32 gigs of RAM on the board, with over half of that GDDR5. So, even if one of these is built they will be expensive. And they will be far less dramatic than other systems. They might "Only" reduce power costs.