It's worth noting that they still have a number of donate buttons on their download page, which Blizzard is supposedly fine with -- all Blizzard wanted was the donate buttons out of the game itself. And of course, if you find this addon (or any other) helpful, you should definitely support the people who make it.
Reaction on the addon's forums is grateful as expected -- lots of people figured that this addon would be shutting down for good, so many are glad to see it will be continuing development. And one developer does say that Carbonite will be removing any obfuscation from their code, as per the new policy, so it's possible that other addon developers will be able to more easily hook into their code and use their techniques. Of course, whether the addon will still be financially worth it for the devs remains to be seen but for now, they're going along with the new policy and widening their audience at the same time.
Thanks to everyone who sent this in!