I'm afraid that this, while a significant decision, will lot mean much in practice. Companies can play cat and mouse indefinitely, and have more resources than hobbyists, if they need their protocols to remain secret.
Also, the ability to run chat bots on the Skype network is something that can be quite valuable for certain companies.
For others proprietary softwares, breaking the compatibility with old versions is hardly conceivable: If Photoshop or AutoCAD where suddenly unable to use read and write the terabytes of data created by their users, those users would probably throw their PC through the window and never buy again a proprietary software...