They can't, the savegame is inside the memory of main.nso, if the file gets bigger (through an update) then the cheats need to be updated. The same goes for code patches.
Just don't update right after it's out if you care about cheats.
New Savegame Pointer is 0x1A846F0, so all codes that start with "580F0000 019D76F0" should work again if you replace "019D76F0" with "01A846F0".
All codes who used the address directly instead of that pointer, need to be updated, like the "Max Action Points" code.
Minimum required firmware is 8.1.0 and it's encrypted using master_key_07, so technically it should work with 7.0.0+.
But maybe they did add something new, because 9.0.0 was made to fix a bug with this game?
Here's to hoping they eventually get updated to 1.0.2.