There have also been talks about legitimizing the services of the app, but that doesn’t seem very possible right now, at least not with its current operational model. The application is based pretty much entirely on illegal content, and giving access to that in a legitimate way would be a huge nightmare for everyone involved in the attempt.
The developers would have to talk to numerous companies and secure licenses that are most definitely out of their reach, and at the same time, since they’ll be forced to look into monetizing the app, users will end up suffering as well. It’s a situation that will not benefit any of the people involved right now.
Unless, of course, we consider the legitimizing of the app a beneficial development, but considering that many users are seemingly fine with using it in its current form right now, that seems to be a bit of a moot point. Cartoon HD may not even need to get its own legal version in order to continue existing.