1. This is mostly done already in either case. If you look at, for example, Unity3D, you work pretty much entirerly with scripts. Today most professional games have a scripting engine and have had it for the last 15 years, since the decoupling benefits are tremendous. Performance wise, game logic isn't heavy unless we're talking physics calculations - But even then much can be offloaded on the GPU using OpenCL or similar technologies.
2. Basicly some token encryption and maybe some proprietary DRM extensions. DRM is, however, all about delivering a crippled product to your customers while letting pirates have a complete and fully functional product.
3. Consoles: See SteamBox, OUYA. But yes, definitely - as long as no AAA games are open source, there is no incentive to develop for it. If you're a small-time developer though, chances are you won't ever get onto the console market in any case. One could of course dual-license, but yeah...