They Won't Publish It And Won't Pay Me!
Developers are busy enough that they shouldn't have to worry about a publisher green-lighting an article proposal and then not publishing the finished article.
Writers are usually expected to sign a contract before they start an article, and it most likely won't obligate a publisher to publish the article. One item, however, which should exist in every contract, is a “kill fee“. A kill fee is where the publisher agrees to pay a percentage of the negotiated fee to the author if the publisher decides not to use the completed and submitted article (as long as the writer has honored the other terms of the contract).
There is no industry standard kill fee rate. It varies from publisher to publisher. Usually kill fees are equal to or less than 50% of the provided fee. Along with the kill fee, all article rights should immediately revert back to the author.
Kill fees are a nice way to help ensure that writers get paid something for their hard work and that the publisher's intentions are honest.