Now that Chrome, Firefox, Edge and Safari stopped or will soon stop supporting NPAPI web plug-ins*, Oracle thought it best to accept the Java plug-in's fate and let it go. The company has announced that it will be deprecated in the next version of Java to come out on September 22nd before being removed entirely by another future release. In its whitepaper, the company said that the "rise of web usage on mobile device[s]" led browser makers to ditch plug-ins altogether. Mobile browsers don't support them, so they've become a casualty in Google's/Mozilla's/Microsoft's/Apple's plans to offer the same features across platforms.
Oracle wrote in its blog:
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.
The Java plug-in is known for being a huge security vulnerability, with at least one report calling it the biggest risk to computers in the US. It's the end of an era for sure -- your browser won't ask if you want to update Java anymore -- but we'll bet you're cool with that.
*Update/Clarification: These desktop browsers still support plug-ins but have dropped (or will soon drop) support for NPAPI plug-ins, in particular. NPAPi plug-ins include Silverlight and Java. In Firefox's case, it won't stop supporting them until the end of 2016.