iirc, N64 titles ranged from 64megabits (or 8megabytes) to 512megabits(64 mB)

SM64 was 64mb, OoT was 256mb, and I believe Pokemon Stadium 2 was 512mb

For DS games, they probably can increase the card size, as long as they read and write in the same manner, but right now I don't think they need to.