I'm not 100% sure how much terrain revamping we'll end up doing myself, as things can start out small and as ideas come and go, get a lot more expansive than originally anticipated. However, what's on the table right now is mainly cleaning up the terrain models not creating entirely new areas (in other words, we'll be sharpening up what's already in the map and fixing errors but there won't be any new sections to correspond more closely to the original - and least not yet). There's also a lot of misaligned textures and underdeveloped areas that could use a sharper aesthetic eye. I got the impression that with the map changing hands a few times (three if I remember correctly) there was a bit of a rush to get things done. I felt the same way with the detention center, hence the reason I'm going to be rebuilding a large portion of that level as well.
I wouldn't expect, for the foreseeable future, that you'll be seeing something closer to your childhood memories but I wouldn't rule it out entirely by the time the mod is finished (as that's likely going to be a very long time from now