Hi,
I think you will need Impala to make Superset working with Kudu. At http://superset.apache.org/#databases it's mentioned the database engine needs '... proper DB-API driver and SQLAlchemy dialect ...' to be usable by Superset. I guess the '...proper DB-API driver ...' is based on JDBC, and there isn't JDBC for Kudu as of now.
As far as I know, there isn't native Superset Kudu connector either. However, contributions are always welcome!
Kind regards,
Alexey