The Carpenters' suit cites the FBT case as a precedent, and if the court follows FBT's ruling then Carpenter has a good chance of success. Another case is currently pending between Sony Music and 19 Entertainment (the producers of American Idol) regarding how labels pay on digital streams. It's the same argument as in the Carpenters' case, but the position of a stream being treated as a license is even stronger than in the digital download scenario. However, it's unclear at this point which way the court will side in both cases.
What should be more of a concern to major labels' fate than royalty rates is the fact that this digital age has made it much easier for artists to be independent and make a living off of making music without major label backing. Major labels can ensure their longevity by creating a new model that involves a deal that artists want to be a part of, that is advantageous to both the label and the artist, and provides for a long-standing working relationship, rather than one where artists are constantly concerned about being taken advantage of by the label. The tighter that major labels hold on to their traditional model, the more artists are going to look for alternative means of pursuing their musical careers -- whether that be making direct relationships with distributors or other scenarios that benefit them financially and allow them to create a sustainable career off making music. This issue is not going away, especially with the growing popularity of streaming as a way of consuming music, and it's time to adapt.