I think developers these days definitely keep streaming in the forefront of their mind when developing online games. Even some story games, like Farcry 5 probably had some influence from the streaming market. That's what it is, a streaming friendly market.

To be honest, I don't really see a downside. Creating a game that is as fun to watch as play offers a lot of potential for the creator to make money, and for the community to make money. The one concern I have is that publishers could get greedy and begin to want to take royalties from those who choose to stream that publishers games. Think Nintendo. As long as that doesn't become mainstream, I could see streaming being very beneficial for video game marketing in the future. Everyone can stand to gain.