Oooh, good wonderings (is that a word? I don't think that's a word... whatever). I kind of doubt that there will be potions again, so far most of those kind of things have not been repeated from one game to the next. ...Well, except for the herbs. But that's been a constant through all of them so... yeah.
I hadn't really thought of the collectibles. That's an interesting thought. Whatever they are, I'm sure they'll be awesome because, hey, LDW itself is awesome! lol

...yeah, I'm going to stop rambling now.