Just suppose you could, and ensure only tales about square jawed white male imperialists win prizes, or that the Hugo Awards from now on will be thinly veiled affirmative action. It might spoil Worldcon, cause some people to look elsewhere for their geek-fix. However in anything like the long term, it would have zero effect on Science Fiction, because…
Science Fiction does not really exist.
Science Fiction is just a label for a literary ecosystem; a feedback loop between publishers, authors, and readers, and it is the readers who determine which books flower, what subgenres thrive.
Reading time is the most precious and private resource. People read, and therefore buy, what they like, not what they should.
So when you say, “This book deserves to be read “– O! The weaseliness of passive constructions — what you really mean is, “Joe(sephine) Rocket Pack should read this book on the way to work, or while waiting for an operation, or when battling depression or feeding a child in the small hours.”
What entitlement! What certainty! And, how very unlikely many of them are listening to you!
Similarly, when you say, “Science Fiction should go in direction X!” what you really mean is, “I think millions of readers should damn well have different tastes than the ones they do have.”
What a bizarre sentiment! Good luck with that!
No, the only way of pwning Science Fiction is by writing, or pushing, books people want to read.
And, in this world of instant online reviewing, the worst fate for a book is for it to land on the wrong person’s e-reader.
That’s why Swords Versus Tanks will be going out with swords and tanks on its Pulp-inspired cover.
It’s also why People with Agendas should avoid trying to foist Approved Books on readers who will then eviscerate them with one-star reviews. I shall watch the fallout with interest…