"Animal Crossing: New Leaf" requires a substantial amount of space that can be accessed very quickly
(since the save chip has to contain practically the entire village, custom interiors included), this type of functionality is exactly why SLC-NAND was implemented in the cartridge. Not only Pokemon doesn't call for that kind of a chip mechanics-wise, there's also a purely economical reasons why such a chip wouldn't be implemented.
After the shortages of
"Animal Crossing: New Leaf" in Japan Iwata issued a statement explaining that the supply of SLC-NAND is very limited as it's not a commonly used or manufactured type of memory.
"Animal Crossing: New Leaf" sold beyond expectations and Nintendo couldn't keep up with re-stocking SLC-NAND just in Japan, let alone the rest of the world.
"Pokemon X/Y" will easily top those sales figures plus it will be released worldwide on the same date unlike
"Animal Crossing: New Leaf" so they need to manufacture an infinitely larger number of cartridges on-schedule.
I don't think Nintendo would be willing to lose money and waste time waiting restocking their sparse supply of SLC-NAND chips that the game didn't even need in the first place rather than pushing as many units as humanly possible worldwide.
SLC-NAND was never an Anti-Piracy measure, it was a necessary evil due to how
"Animal Crossing: New Leaf" works. The mechanics which necessitated its use will
not be present in
"Pokemon X/Y".
tl;dr I would be quite surprised if SLC-NAND was be on
"Pokemon X/Y" cartridges.