Well, I can't really see why not. License the engine and provide support to commercial projects and let the community have it for free. In the end, you get free marketing from it, because anyone can pick it up and run with it. Many of the big game engines/games have SDKs anyway, which allow a lot of customization... this is just the next step and it makes total sense.
No announcement yet.
Huh, id Tech 5 Engine To Be Open-Source?