From the blog post on FamilySearch:
Beginning December 13, 2017, patrons visiting FamilySearch.org will see a prompt to register for a free FamilySearch account or to sign in to their existing account to continue enjoying all the free expanded benefits FamilySearch has to offer.
We’re just passing this along. The free account (I’ve had one for years and am not an LDS-member) will be required to view digital images of microfilm and records. Some digital images likely will still require onsite access at the Family History Library in Salt Lake City or a local Family History Center to access.