Eurodance, if you read back, several forum members /customers who contacted Apple are already testing a beta WiFi fix. Some say fix worked, some say fix did not work. To be clear, first fix attempt is being field tested right now - with Apple collecting more data. Apple does not want "back to school" sales negatively influenced, there is precious little time, they will get it right or answer to stockholders.
As a comparison, if you search on "2013 Macbook Pro Retina fan problems" you'll see a thread almost this long. Apple released a firmware upgrade about a week after the fan issue lit up major blogs. This was all going on about the same time reliable sources were predicting new MBA a/c WiFi, so I decided to wait a bit longer, switch from MBPr, to MBA. My rationale was also a sense that 12 hour battery life is probably not happening for a Retina display any time soon. I personally prioritize 12 hour battery life and faster WiFi over 13" HD screen. I have a home theater to watch movies.
So, about a week after this new WiFi issue lit up the blogosphere, Apple has released a first fix attempt. I'm not excusing Apple, I don't know enough about a/c technology vs. a/b/g/n, but it seems perhaps a/c is more challenging. I don't think Apple purposely sabotaged connectivity of its flagship new laptop. I'm not an engineer, but I do wonder if a significantly faster technology can be compatible with 100% of the mllions of legacy routers. I don't think anyone knows the answer to that, yet.
Some forum members have noted they have traveled in Europe with a new MBA without WiFi incident, but I'm not sure I buy into the theory this is organic only to routers in the United States. I think it's also fair to observe the a/c standard is not even yet officially approved.
What I do suggest with confidence, the WiFi issue will be sorted by end of July. Apple store employees can't possibly flash all the base config MBA's 'in the wild' waiting to be purchased. Those will get upgraded by the customer at first-start up/install via internet update.
It seems to me, custom builds will be first to have the fix preinstalled and ready out of the box.
Just my two cents.