I don't know if they are saying that this is an altruistic act, a task they are charged with by their colleagues at Sibelius, or if they are doing it because they want to create a new version of Sibelius that will take advantage of the new features in the MuseScore package.
We've been working with the Sibelius team to find a good solution for supporting the older versions. We've looked at a few options, and decided that the only sensible way forward is to create a new version of MuseScore for Sibelius 8.0 and above.
Since it sounds like Sibelius 8 will probably be the last version of the program to get new features, it seems likely that MuseScore will continue to develop MuseScore for Sibelius 8. (And the fact that the version number changed from 7.0 to 8.0 indicates that there were some features added.) 827ec27edc