As for newer tech, that's been happening from time to time: bigger and better ASIC's
As I said, I am not a math or algorythm expert but... It is not possible to find another way to calculate the hashes that cuts the process short?
I have also heard that Scrypt/Litecoin was designed to be ASIC resistant but failed. Could not something similar happen to Bitcoin in such a long timespan as 100+ years?
There is none, and bitcoin was designed to be harder to mine as more and more powerful hardware come. More and more hashing power = more difficulty = harder to mine bitcoins.