This will begin impacting users in April, this year. Below is a note from Tridium:
Oracle has announced the pending end-of-life of Java SE 8 (Standard Edition). As of January 2019, free public updates are no longer available. Customers accessing Niagara with the Java Applet/Web Start will be impacted by this change. Those who have upgraded to full HTML5 versions for their browser front-end will not be affected. For customers who use the Java VM and Java Web Start for their legacy systems, Tridium is actively developing a suitable alternative.
UPDATE: Starting with the April 2019 scheduled quarterly critical patch update from Oracle, Commercial Users will have access to updates through My Oracle Support for their Java Applet/Web Start. Or users can begin utilizing the Niagara alternative, Niagara Web Launcher, which is currently scheduled to be available in mid-March.