I don't see it succeeding unless they get Riot Games to exclusively stream on YouTube. That amount of views League of Legends brings to Twitch is crazy.
Amazon doesn't have YouTube's experience, and is somewhat short-sighted when it comes to catering to content creators. Maybe Twitch employees could help.
Haven't been following LCS for 2 years or so, but they used to stream it on multiple platforms at the same time.
I don't think Google can pay RIOT enough to go exclusive, especially since they need to be able to stream and get revenue from multiple regions, especially China.
This would be a good time to be a streamer with a lot of fans to get in a little bidding war between Amazon and Google.