While there is logic to a part of their argument, I don't buy that it should take that long. Just looking at the numbers you can understand that a couple months of decreased output when you're talking about meeting a quarterly demand that reaches between 145 and 160 million units. Don't recall precisely, but if those plants were already working at full capacity when they went down, and no new plants have been built in the nine or so months since, it isn't unreasonable that they would have a little trouble catching up with demand again.
That being said, prices are already coming down and should continue to do so until they do reach their former pre-flood price level. The only impediment will be demand. As long as demand remains high they won't have any incentive to drop prices any faster. They'll keep putting a new floor in to make more money, milking the continued hesitance of average consumers to jump in with SSDs.
Finally, I would note that this is an IHS report. They're analysts and researchers, which means they're making a best educated guess. They could very well change their mind tomorrow if someone showed them something different. No need to worry too much.