Having started with Cakewalk for MS-DOS a few decades ago (after graduating from the C-64/SX-64 and Dr. T's KCS to an 8086/8088-based MS-DOS system), the demise of Cakewalk hits hard. That being said, as "legacy" software SONAR (and related software) will probably continue to be used for quite a while by those of us who have grown accustomed to its face--until such time that Windows/Microsoft does updates/upgrades/outdates that render the software incapable of being run on current and future PCs. My guess is the code and formats will probably not be open-sourced, although that might be nice if it were made available.
Steve