>Bets on how long until that become a link straight to Amazon to buy said game, and how long until streamers become Amazon affiliates and start getting money for driving people to buy their games off Amazon?
For 1, it could easily happen. For 2, already happening. I see lots of streams put buy links to Amazon in their channel description.
IMDB (owned by Amazon) doesn't have buy links on their site from movies (at least none I could see), but it does have a stream on Amazon Prime.
>Because that's the only angle I can see Amazon having here: trying to get gamers to grab games off Amazon. (And they do sell digital game downloads, so they do compete with things like Steam.)
Buying games has a really small profit margin. Twitch allows Amazon to expand further into the gaming market itself. As for #2, you are right, but just to make things clear: a lot of games you buy from Amazon include a Steam key. Steam doesn't really use vendor lock in. You are free to generate an unlimited number of steam keys for your product at no cost, and sell those keys though any channel you want.
Disclaimer: I am an Amazon employee. Everything I said here is my own opinion, and guesswork. I do not work for the gaming division of Amazon, nor do I have insights into what they do.