From the update:
There has been a lot of discussion about expansion ad-ons and we worked really hard to change things around in a way that made the most sense. I will go into specific detail below however it should be noted that that the expansions have doubled in size overall and we are adding a new trope to enjoy. The expansion changes we have made are intended to provide base level pledgers the opportunity to have access to add-ons while at the same time providing more rewards for the wagon masters. This is a very tough area to find just the right amount of balance. That being said I think you will see that we tried to make everyone happy and provide even more content and fun stuff to the game. The last important note here is that we are going to add additional $75 wagon master spaces to give people an opportunity to jump in at a lower level now that we have made these new changes.
We are dividing the expansions into 2 groups High Lows and Trails and Tropes. This will provide the flexibility to offer Highs and Lows to everyone as an add-on (see our reasoning below). The Trails and Tropes will remain in the Wagon Master pledge level as a deluxe exclusive along with a new third trope as well as receiving the new expanded Highs and Lows. This new direction for expansions is meant to provide some add-ons for the base level while keeping the Wagon Master level special.