Limited Pack Obelisk Blue cards
With the reveal of the Ra Yellow pack finally happening, it's clear we are probably getting a new limited pack each year to coincide with the Gx remaster, so next year should be the blue pack with season 3 cards. I was curious what cards there were from season 2, so and went a checked and there is around 126 cards that debuted in season 3 which could be chosen (provided I didn't miscount or miss any cards):
Ritual of the Ultimate Forbidden Lord
Several of these cards I doubt will be picked for this pack like the Wicked Runes, but there are some interesting things which could be chosen. This is most likely where we would see SFG printed despite it not visually appearing, and I wouldn't be surprised if some random monsters like Anchor Knight got printed as well.