Nintendo and fifty-three other companies are filing a suit against retailers selling flash carts, demanding that they stop the sales and imports of said cards. According to Kotaku, Japanese retailers in Akihabara are noticing a difference in demand for flash cards already. Regarding the R4, one staffer noted, "The rush in demand has been amazing. These devices always sell well. But this weekend should be staggering, don't you think?" Amazon.jp has also seen a rise in cart sales, which is to be expected.
We're sure Nintendo foresaw the immediate panic following the company's announcement, and that's the risk they decided to take -- watching things get worse before they get better. If Nintendo and the others win the suit, though, it will likely be worth their while in the end.