On 4th November 2013, Oracle announced the future for GlassFish. GlassFish Open Source Edition 4.1 will be released in 2014, however the commercial edition (Oracle GlassFish Server) will no longer be supported.
For production, meaning Java EE 7 applications which already use GlassFish, you either stick with an unsupported platform or find an alternative solution. That said, even open source projects relying on GlassFish may consider a change eventually, if the updates become less frequent as the demand from the commercial side is removed.
Currently, the number of platforms supporting Java EE 7 is very limited; the answer could lie with Red Hat application servers. WildFly is the new open source JBoss Application Server developed against the Java EE 7 Reference Implementation. A stable version (WildFly 8) was released February 2014. Additionally, Red Hat continues to provide a commercial version called JBoss Enterprise Application Platform.
Open-source GlassFish is planned to continue at least through version 5, which will support Java EE 8 Reference Implementation, but the question remains as to whether anyone will use GlassFish in the future.