we're able to make more processes per second, with less power, so in a sense it becomes cheaper to perform these processes which means the overall value of a bit-coin goes down ...
Is this a correct interpretation of how mining works ?
That means that difficulty will go up, which means that people who invested in the current cards generation will earn less bitcoins because there are bigger players in the network.
We have not found a strong relation between difficulty and price yet. The price could go down because sellers are willing to sell for less, but speculators may not have the same opinion.