As I read it, they hire you if you have a good idea for a game addition and that's it. That's how freelancing works, you get paid an agreed amount and everything you created is now their property. That doesn't seem too bad, some modders will want to have a go at it, most other probably not. What worries me a lot more is that future content is split into hundreds of tiny portions that will all have to bought seperately, and from my experience, stuff you have to buy with dedicated credits in a dedicated shop is almost always more expensive than any DLC. And who knows if there will be any bundles and a discount eventually, I kind of doubt it.