If, and that is a big if, BFL do indeed get their ASIC's to market within the next 3-4 months it would make the mining of Bitcoins a lot more difficult. How much more difficult would be hard to say as it would be based on the hash rate increase on the network, not as they ship in anticipation as you stated. We don't know how many units have been sold or in what configuration.

Even if they don't deliver as promised, it's a matter of time before some company or many companies start to mass produce ASIC's, rendering standard AMD (ATI) graphics card mining redundant.

When this happens it starts getting interesting as there will be more trade to acquire Bitcoins. The price will rise and those who have been hoarding will start selling. More business will start accepting and eventually the Bitcoin 'stock' that is traded on MtGox etc will become the currency it was designed to be.

Of course, this is based on speculation on my side that there will be green lights from all the banks and governments of the world. Highly unluckily but with a revolution or two we'll be just fine.