I don't think unlocking plugins to work in other daws will increase loyalty to Sonar. Let's face it if folks are going to use those plugins in other daws they're not working in Sonar. It makes it just another grab for something free. The way it is now means of people use the plugins they're working in Sonar..
The fact that I may use another DAW isn't because I want to, it's usually because some circumstance forces me to use that particular DAW. For collaboration usually. So if that's the case the other party won't have the Sonar plugins anyway.
The fact that a few plugins are unlocked and work in other daws should be seen as a plus rather than a reason why others should also be. When I've bought other DAWS it's never been because of the included plugins. It's just not a selling point for those of us buying multiple DAWs. On the the other hand, a new user can buy a DAW like Sonar and be pretty much set to go, being able to start and complete projects from beginner to professional levels.
I will say however, that there's only been one packaged plugin that I want to use in every DAW and that's Sony's Wave Hammer. The absolute best brick wall limiter there is. DX only.