Oracle have recently announced via a blog post that they are going to deprecate the Java browser plug in JDK9 and remove it from future releases.

By late 2015, many browser vendors have either removed or announced timelines for the removal of standards based plugin support, eliminating the ability to embed Flash, Silverlight, Java and other plugin based technologies.

With modern browser vendors working to restrict and reduce plugin support in their products, developers of applications that rely on the Java browser plugin need to consider alternative options such as migrating from Java Applets (which rely on a browser plugin) to the plugin-free Java Web Start technology.

Oracle plans to deprecate the Java browser plugin in JDK 9. This technology will be removed from the Oracle JDK and JRE in a future Java SE release.

Early Access releases of JDK 9 are available for download and testing at http://jdk9.java.net. More background and information about different migration options can be found in this short whitepaper from Oracle.

Source: https://blogs.oracle.com/java-platform-group/entry/moving_to_a_plugin_free

Most browsers are already removing plugin support or don’t support extensions any more. See links below:

• Firefox
  
• Edge
• Chrome

Oracle are addressing this through their Java Web Start which downloads the relevant files to your computer if not present then caches them for later use.

Java Web Start is an application-deployment technology that gives you the power to launch full-featured applications with a single click from your Web browser. You can now download and launch applications, such as a complete spreadsheet program or an Internet chat client, without going through complicated installation procedures.

Java Web Start includes the security features of the Java platform, so the integrity of your data and files is never compromised. In addition, Java Web Start technology enables you to use the latest Java SE technology with any browser.

With Java Web Start, you launch applications simply by clicking on a Web page link. If the application is not present on your computer, Java Web Start automatically downloads all necessary files. It then caches the files on your computer so the application is always ready to be relaunched anytime you want—either from an icon on your desktop or from the browser link. And no matter which method you use to launch the application, the most current version of the application is always presented to you.

Source: http://docs.oracle.com/javase/8/docs/technotes/guides/javaws/

However this may not be plain sailing as pointed out in this blog post from Openmicroscopy

What does it mean for desktop developers/administrators?

To deploy Java Web Start, one first needs to get familiar with Deployment Rule Sets. Administrators can then create a list of known-safe applications and manage compatibility between different versions of Java on the system. Each browser will have their own set of dialogs and control mechanisms.

It is getting harder and harder to distribute Java Web Start applications for developers and/or administrators.

Source: http://blog.openmicroscopy.org/tech-issues/future-plans/2015/09/23/java-web-start/

Other useful reads:

NPAPI Plugin Perspectives and the Oracle JRE