That was my only concern. They say first come, first server which may turn into 4th quarter at this point. By then, video cards will be pointless and a 5Ghash may be the equivalent of my 7970 today.
There is no question in my mind that someday it will be just that. But it's really hard to say how soon the difficulty will "catch up" and make even ASIC profit slow down. It seems that all of the ASIC manufacturers are having trouble shipping in bulk in a timely manner. It might take years before enough items ship to really kill the profit.
And of course difficulty is only part of the equation, if price goes up or down that can throw everything off.
Now, I could be way off here, but this is my theory:
Mining on a GPU is highly profitable now. It has almost always been at least somewhat profitable, at least with my power costs, even when bitcoin crashed hard after $31.90 high of 2011 mining profits were still greater than electricity cost. Now, the total bitcoin produced is a static number. The more people in the mining game, the smaller my share gets. Still, it has always been somewhat profitable.
On an ASIC, I think the same basics will apply- mining on an ASIC will be profitable to a degree for a long time, even if value crashes. Someday newer ASIC built on a more advanced process might replace the current devices, but I think that is a long way off. But here is the difference: every gamer with a bit of brains and an AMD video card can bitcoin mine today, and many do. When ASICs are more readily available, this won't be the case anymore- only dedicated miners who buy ASICs will be mining. Instead of competing with 10000 AMD video card using gamers, I'll be competing with 2000 ASIC using professional miners. All in all I feel that the shift to ASIC will cut down the competition, and in turn my effective profit will be a little higher than it would otherwise be.
In any case, I pre-ordered before the price hike too, so that helps. I'm less inclined to buy a 50GH single for $2500, the 60GH single for $1200 was a significantly better deal. Though, I might just order a jalapeno or two to supplement my singles because I think it would be a neat little conversation starter.