Agreed. Citi has paid almost $1000 of my student loans at this point!
I got that email as well, but my statement cut today and all is well; still getting 5x on everything. Fun little fact: Everything food-related that I used the card for at Disneyland counted as a restaurant! From Blue Bayou and Carthay Circle to the ice cream stand that sells those amazing Dole Whips, they all counted as restaurants 
I think that eventually the 5x categories will be discontinued because, honestly, this card is just way too good of a card for Citi, or anybody, to keep going. But for now I think all we have are baseless rumors and no reason to worry until someone actually gets their card nerfed.
May 2013