There were four witches in the Oz books. The "Wicked" books and musical just used what already existed with some literary license.
As far as "The Lone Ranger" goes, it looks like it's being marketed better than "John Carter" was, not that that is difficult. Personally, I was pumped about both of them but what I've seen of Lone Ranger, apart from Depp being in it, it looks pretty mediocre. John Carter, if it would have had a better lead actor (and Hammer isn't exactly a riveting actor for the Ranger) and some kind of selling done for it, could have had a chance.
"Oz" could be GREAT as long as it stays away from modern dialogue, references, sarcasm and attempts at "smart-" humor. I've seen some of that in trailers and it is discouraging. It takes place in the late nineteenth or early twentieth century so keep the dialogue real.