[Question] What Keeps Steem From Being Diluted By New Posts?

What keeps the value of Steem & Steem Power over time? As new top posts are paying out large sums, what ensures there won't be a massive influx of Steem that would dilute the value of indiviudals who have already earned their steem? Basically, what is the inflation protocol for Steem, similar to how Bitcoin has the bloc reward halvenings.