I'm fairly new to bitcoin mining but I have read enough now to understand many of the ins and outs of mining.

One big question stands out in terms of long term gains with mining. Since this is an actual currency, every time a new generation of cards is released we see effectively the newer version having 2x the horsepower of a card from the previous generation. So lets assume the 7000 series comes out and we all swap our 6990's for 7000 ... great ... that means 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  ?