Until 1 January 2017, can a Party to the STCW Convention continue to renew and revalidate certificates and endorsements in accordance with STCW 95?

Yes. 

STCW.7/Circ.16 advises as follows: “Regulation I/15 provides that a Party may, until 1 January 2017, continue to renew and revalidate certificates and endorsements in accordance with the provisions of the Convention which applied immediately prior to 1 January 2012.”