Please stop panicking. I have 3 Fury Xs folding 24/7. 2 of them are in the same system. Stock coolers as well. I had them roughly similar amount of time as Matt did. The difference is I was 24/7 folding on them while Matt probably was just gaming on them and switching them off at night/during day. On the other hand I was less inclined to play around with voltages and clocks as Matt was.
Either way, one dead fury x will never mean that all of them are going to die.
I was more concerned it was a subtle way of letting us users know some of our cards might give out to soften the blow, I found it unusual to read.