@ Rythal,
I noticed your comment, that most people would prefer to stick with Carbonite rather than try something new and that this was one of the reasons you were reluctant to start from scratch, (besides the hideous amount of work involved)
So I just thought i would throw in my opinion, ever since 5.0.4 hit last week i've been trawling the internet with the search term "Carbonite Replacement" or "Carbonite type map add-on" and tonight discovered this post.
My point, is that i cant be the only one searching Google, Curse, anywhere they can think of with these search terms. As some of the other posts have suggested, the support and the response (or lack of) from the original developers has alienated some players, regardless of whether you had created a fan update or not, people would still have been looking to dump carbonite as it is, and replace it with something that will work in MoP.
Carbonite was a great add-on and the original developers did a great job. But if it no longer works then it isn't an add-on any more, its just a piece of history.
I know people may say we are all being a bit premature and that its an add-on for a game but its a game millions play. Maybe it is unrealistic to expect a working version on patch day (even though most other major add-ons were done on the day or just after) but it wouldn't take a minute to post on this forum and say "guys we're working on it, its on its way!", i know we would all be happy with that.
Given the response on this thread alone, i'd say people would be more than happy to use a new add-on (whatever you call it) if you chose to write one.
If you want the challenge and you are able to create a legal replacement, i'm sure the community will stand behind you and help where they can. You've provided better feedback and interraction with the user community than most software vendors. Plus, we've already seen you know what you're doing, because you've created a working replacement over a very short period of time.
Obviously none of us want you to break the law, but if Carbonite is going to die then someone will eventually design a replacement, why not you?
As I say, the most important thing is 1) that you want to do it and 2) that you can do it legally, after that anything is possible.
Just my opinion, but i just wanted to add my voice to the support for a carbonite type add-on, whatever its called, as long as it works
And in the meantime, a huge THANKS for the work you've done so far. I really can't tell you how happy you've made us all.