Knol will not be available for viewing from May 2012.
Google provided a migration path to Annotum hosted on Wordpress, a blogging platform. Google can provide a migration path to Blogger also and let authors choose where they want to go. Providing a migration path to Blogger should not cause big burden to Google and many knol authors are on blog already and they will be in familiar territory.
Google needs to consider this alternative migration path as demand of Knol authors.