Yeah, you're going to want to use some kind of "freeze a working stack of technology in time" approach, and then probably make sure that it only talks to your music server. There's no guarantee that a Flash Player from 2020 is going to work on future operating system versions (that's work that we're constantly doing behind the scenes), so you'd probably want to build a virtual machine image where everything works, and that you know will run in emulation on whatever the latest thing you're running is.
I have to admit to some confusion regarding what will happen after flash becomes obsolete. I teach and develop training and use powerpoint with embedded flash files for interaction. I output the presentation to PDF and then place the animations in the PDF using Acrobat. I suppose I'll have to migrate to captivate and start using powerpoint animations instead (yuck) but I'm hoping tI'll figure out other options as I research this more thorougly. However, the confusion is related to folks who keep saying to use HTML5 and Java to create animations. It won't be long until browsers no longer support Java as it's an even worse security risk than Flash. What's a developer to do? My guess is that Captivate outputs animations as either shockwave or java as well so Captivate doesn't seem like the long-term solution. What's a content developer to do?