Fun fact, the ETB holds 3 large Japanese boxes perfectly. I like the bigger boxes, with the smaller ones the deck fits too well into the box and it's almost a pain to get out.
For prereleases, doesn't Magic have a separate prerelease box that is much smaller than a fat pack? Couldn't all the contents of the ETB be placed into a smaller "Prerelease Kit"? Same contents, just no storage box.
I would like TPCi to do prereleases like you just said, except have the person have a choice between 2 promos, like when you go to a video game store, and you only have the budget to only buy either Pokemon X, or Pokemon Y. The whole 2 promo thing is good, because it gives the same feeling how there are 2 Pokemon games, not just one. So here is how it works:
For sets that only have one Japanese Booster, or none, or any sets that corresponds to one Japanese booster set, like Emerging Powers, Noble Victories, Dark Explorers, Plasma Storm, Plasma Blast, and Legendary Treasures etc. will be like any prerelease. One promo, and 6 packs, all the same.
The sets that include 2 prerelease promos would be sets that are based off the Japanese sets that have 2 different booster sets, or sets that decides to combine 2 Japanese boosters from different release dates, like what we have for XY, Plasma Freeze, Boundaries Crossed, Dragons Exalted, Next Destinies, etc. Players are given one of two choices. The choice you make will mean that you get one promo, and not the other. Another difference between the 2 choices are that 2 of the 6 booster packs aren't exactly the same booster pack you will buy in stores, but are more like the exact same booster pack as the Japanese counterpart. Let's say the XY prerelease used this model. 4 of the boosters will be the XY set, which combines the Japanese Collection X and Collection Y, as well as the Xerneas Deck and Yveltal Deck. The 2 packs that are different from the rest of them, and let's say you picked the X themed prerelease set, you will get 9 card packs that come from the Collection X + Xerneas deck card pool. This means 2 of your packs are guaranteed to not have certain cards, like Blastoise EX, because you didn't pick the other prerelease kit.