I seem to recall there was a way to play .swf files without a browser. It might be cool to see a standalone flash player, maybe a little like the Electron framework.
> Letting flash run outside the browser sandbox, what could go wrong?
It would be like any other desktop application. You're running code of which you presumably know and trust the provenance. It's not like a malware Flash ad written by someone who found a security hole in the Flash player, that is loaded into a random web page by an unsuspecting user.
