These days, Kickstarter is a different place. We understand we're funding the creator to try their best. Sometimes things don't work out, and that's okay; we take on that risk as backers. But we're also entitled to your progress.
Six years after the space simulation game Limit Theory earned $190k, the author finally gave up. I think he handled it very gracefully and most people were empathetic, so this isn't a criticism of him. He said he plans to open source all the game's code and assets. If he does, I think he'll come out on top. But it should have been that way from the start. Two weeks after the announcement, he is understandably MIA, but I have to wonder how difficult it is to push code to GitHub (or elsewhere).
If you're asking for people to believe in you and open their wallets, you owe them at the very least the ability to claim your efforts at any point. I don't care if you promise from the start that your end result will be "open source." If you don't give me a link to a public repo, I cannot support you. If your project is not code, you can publish a Dropbox (etc.) link on your crowdfunding campaign and work exclusively from it. You should include a license that gives us the explicit legal right to copy, share, and improve your work for any purpose. That way if you change your mind, suffer some horrible tragedy, or otherwise disappear, there is always the option for many people to pick up where you left off. Maybe it will even give you the peace of mind that you don't owe us anything at any point!
As a side note: I propose that someone creates a crowdfunding platform which requires all projects to include a source repository and free culture license (with moderators who enforce this). The platform should of course be free software.