The UK Parliament has released an uncorrected transcript of "House of Commons Oral Evidence Taken before the Business, Innovation And Skills Committee Open Access."
Here's an excerpt (below comments by Alicia Wise, Director of Universal Access, Reed Elsevier):
With the Government's policy that we are all implementing, we will see an increase in the amount of hybrid open-access publishing done at scale. For the open-access components of that hybrid publishing, it is clear that the costs are sustainable through the article-publishing charges. For the subscription part of those titles, the costs continue to need to be covered through the subscription model. If the content is freely available too quickly, there will be no need for libraries to continue to pay those subscription costs. While we have not seen clear evidence of an undermining or cancellation of subscriptions at this point, there is evidence, such as that Audrey referred to, that librarians are watching this space very closely and are very mindful of it. We have also seen that where content is deposited at scale, there can be an erosion of transactional revenues-the pay-per-view business model. Those are very modest components of most of our revenue streams, but again it is a potential early-warning sign.
See also the video of the session.