As you said, Oracle has recently announced some news regarding an end of public updates of Java SE 8. Fortunately, it doesn't mean that Oracle will start charging for Java from now on. As a matter of fact, it means that since January 2019 Oracle won't provide support and regular updates to Oracle Java SE 8 for the public, they will provide updates and enhancements only for commercial users (paying customers). For more information please see an article "Is Oracle really charging for Oracle Java?"
and links included in that article.
Therefore, if we upgrade to Java 9 or above, we don't need to pay anything for now. As it is stated in the article, in case you decide to upgrade to CloverDX 5.0 and higher, Java 9 is officially supported with it. Also, with CloverDX 5.2 that is supposed to be released in the first half of the year 2019, it has been decided to start supporting also Java 11 (Oracle Java SE 11 is the next planned Long-Term Support release) and as we can see the inquiry for more options then just OracleJDK, we are also going to support OpenJDK along with the CloverDX version 5.2.
I hope this helps. Best Regards, Eva