There are at least two transition issues related to the publication of ISO 13485:2016, certificates and status as an EU Harmonized Standard.
ISO 13485:2016 has a publication date of March 1, 2016. ISO/TC 210/WG1 recommends a transition scheme for certificates. Two years after publication (March 1, 2018), all new or recerifications should be to ISO 13485:2016. Three years after publication (March 1, 2019), ISO 13485:2016 certificates will not be valid. The accreditation bodies must act on this recommendation.
The second is the recognition of EN ISO 13485:2016 as a harmonized standard to the European directives. It is not yet a harmonized standard, but should be harmonized before June 30, 2016. Another issue is the date of cession of presumption of conformity for EN ISO 13485:2012. Technically, we don’t know this, since it has not yet been harmonized. However, it is usually the date of withdrawal, DOW, set by the European standardization organization. In this case, CEN has set the DOW as March 31, 2019.