If you backed the Wii U version and are happy to have the game on Switch, you don't need to do anything - your pledge will automatically be changed to the Switch edition. If you want to change to one of the other consoles - PC, PS4, Xbox One, or Vita - then you need to amend your backer survey.
If you don't want a Switch version or any other, then you can apply for a refund - as long as you pledged at least $28 and you're willing to accept a PayPal payment. The refund request has to be submitted before April 20th.
Here's the statement from Koji Igarashi himself:
Hello, this is IGA.
Thank you for always supporting us. I would like to give a message to the backers who pledged for the Wii U version of Bloodstained.
During our Kickstarter campaign, the Wii U was at the height of its popularity, but the situation has drastically changed after the release of Nintendo Switch.
This change made it difficult to receive the necessary support from the hardware maker, which has led us to drop the Wii U development and shift the development to Nintendo Switch.
We are very sorry that it has come to this after all your support, but we hope you will understand. We would like to respond by preparing options for our backers, such as moving your pledge to another version or requesting a refund if you don't want any other version.
We hope you will continue to support us.
How do you feel about this news? Were you holding out for the Wii U version, or are you perfectly happy with getting this on Switch instead? Let us know with a comment.