It was very confusing until it was explained to me. So, in my understanding, DAO and Splinterlands relationship is same as of a movie producer and director.
DAO, a separate entity from Splinterlands who is governed by SPS holders, would be giving funds for producing Rebellion packs. Splinterlands, the devs, would be doing the hard work of making the card design, implementing it in the game, etc.
Since the DAO is the one who funded this, DAO would have the higher share of funds on the sale. Splinterlands would get a part of it, depending on the contract between the two.
Before, in my understanding, what happened is Splinterlands is shouldering everything, and DAO gets a part of it (contrast of what this proposal is). Before, it's more like, everything is funded and done by Splinterlands and a small part is donated to the DAO entity. Now, what they want to do is for DAO to shoulder the expense but in return, get more of the sale then a small part of it will be going to Splinterlands, depending on the contract between the two.