Yesterday I've read this article from Dave Hay (thanks) that was remind me the EOS of JAVA 6SE.
The date is set to April 2018 for traditional WebSphere and September 2017 for WebSphere Liberty Profile.
Others WAS version prior 8.5.5 will not have support of new JRE so must be dismissed to maintain System Security. Java 7 will not be the best migration path because have already set EOL to 2019.
This is a table about Java supported version and WebSphere version
For traditional WebSphere 8.5.5 the step required will be upgrade at least to FP9 ,than install Java SE 8 , than set the default SDK to 8.
Obviously the applications must be able to run with the updated SDK . IBM has build a migration toolkit to scan and analyze your Java apps and check compatibility differences.
Regarding IBM collaboration software like IBM Connections , right now only Java 6 SE is supported so probably during next month IBM will release a CR able to support Java 8 except for Connections 4.5 that have EOS April 2018.
To read more details about J6SE EOL please read this article.