So I didn't get it. What will be inside the generations booster pack?
If it's what I think it is then it will be reprints from each set that came out in that particular generation/time. So first mew box will have reprints from Base set, jungle and fossil. Maybe make newer versions of these cards where they have the same attacks, slightly updated artwork (like scyther, electabuzz, hitmonchan and charizard line reprints in DP era), but attack cost less, hp more?
The other thing it could be, is a mini set for that particular generation a bit like the pop series boosters we used to have with like what was it 2/3 cards in them?