It was suggested that a hardfork variant would involve placing the signatures in another parallel merkle tree, allowing users to validate everything but the signatures if they wished, and that this would not affect TXIDs. The idea behind a softfork is less clear, but will reportedly be discussed at the Scaling Bitcoin HK event. Links were provided to more information on the subject, including Github pages and PDFs. However, there seemed to be a lack of comprehensive information available on segregated witness.