No doubt APEX is here to stay!
In 2005 there were some doubts about APEX future, former HTMLDB. Oracle made it quite simple to show its commitment in the end of 2005 by releasing their rewrited Metalink support site using their own APEX technology.
If any of you still have some doubts about it, Oracle used APEX technology on Oracle Audit Vault (10.2.3) incorporating Interactive Reporting and Runtime-Only APEX capabilities to provide their users highly customizable reporting capabilities. You can read further about at David Peake Blog.