Well my personal interest is in editing the HUD/score overlay - I'd be delighted if there was essentially full control over what's shown where and when, and a simple way to just throw in more textures when I need them.Who would be the "go to" mod guy here? I want to make sure we expose as many files as makes sense (not the executable) or make the "blob set" as accessible as possible.
If it's at all possible at this point in the design - having the ability for the game to pick up files out of a particular directory would be ideal - the games in the past that have needed people to import into the blob files have been much harder for users to work with.
It would be perfect for example if you could replicate the blob structure in an open folder - and the game go there to pick up things by default, and then let the game access an unalterable original blob for when it needs to go online or otherwise needs to be in an unedited state.