Popcorn, they won't release any sort of software to edit the files. I can't count the number of games out there that have used notepad to mod them. What we'll get most likely as far as modding is a plugin to make the models the correct format and a map editor.
And why would I edit XML files if they release mod software? Becuase it teaches you the real code and how it interacts with everyhting. Oh and one other thing. With notepad i'll be able to start modding as soon as I get the game.