"If I am unable to complete my project as listed, what should I do?
If you are unable to fulfill the promises made to backers, cannot complete the project as advertised, or decide to abandon the project for any reason, you are expected to cancel funding. A failure to do so could result in damage to your reputation or even legal action on behalf of your backers."
So definitely it's possible that your backers could start a class action lawsuit and sue you because you took their money and didn't deliver a product, but this would require some organization on the backers' part, kickstarter wouldn't do this on their behalf.
"If I am unable to complete my project as listed, what should I do?
If you are unable to fulfill the promises made to backers, cannot complete the project as advertised, or decide to abandon the project for any reason, you are expected to cancel funding. A failure to do so could result in damage to your reputation or even legal action on behalf of your backers."
So definitely it's possible that your backers could start a class action lawsuit and sue you because you took their money and didn't deliver a product, but this would require some organization on the backers' part, kickstarter wouldn't do this on their behalf.