Well, I have a 2016 r4isdhc gold pro card, and I went to play it yesterday. When I opened it up, it said firm expired blah blah blah, and I was like wtf. So I went to the date/time on my 3ds, and it reset itself to the year 2028 lol. And I was like crap.. did my flashcard brick itself.. so I turned the year back to 2010 and started up my flashcard....
Guess what.. it worked! So they don't brick... Just make sure when you use it you don't go past the year it says on it