acekard 2i works too, i believe in gbatemp they mentioned that this update wasnt blocking any flashcarts at all
Yes, iluvfupaburgers is correct, The new 3DS firmware 2.1.0-4 didn;t block any flashcard, it has been confirmed that Acekard 2i, DSTWo and R4i gold 3DS are stilll working on it without update. I think other other cards also work well.
I tried my flashcards-Acekard 2i 4i SDHC 3DS R4i GOLD 3ds, they all works well with the new firmware. It seems will not bloack any flashcard.
They aren't gonna block flashcards for normal DS games. I guess they're just setting up an AP for the 3DS in the (rare) case flashcards for the 3DS are coming. I hope they will succeed because I will not be using flashcards for the 3DS.