Currently Oracle has not released any information about the next Java SE exams and the general public does not know which version of Java the next exams will cover or when it may even be released.
I suspect that Oracle is still evaluating their options as they move forward finding the best balance on certifications for Java versions.
In the past it has taken Oracle more then a few months to get an beta exam together and then a month or two after that the beta exam was replaced with a general non beta exam.
However Oracle has now stated that they plan on using a rapid release schedule for Java, where they plan on releasing two versions of Java a year.
If Oracle follows though with the rapid release schedule then by the time an exam was made available a newer version of Java would be out.
Oracle has also stated that some versions of Java will be considered long term releases which will enjoy extra support.
According to http://www.oracle.com/technetwork/java/eol-135779.html Java 11 will have extended support once released, but Java 9 and Java 10 will not.
Currently no one knows what exactly the rapid release schedule will have on the Java certifications.
Many people have used study guides in the past to help prepare for certifications and at the very earliest one may see a study guide for the next Java SE certification a few weeks after the general availability of the exam.
If you are looking for a path forward I suggest that you get the OCP Java 8 certification. In the past Oracle has allow one to go straight from OCP Java 7 to OCP Java 8 with only one exam.
After you get your OCP Java 8 certification start learning Java 9. There are many books and resources for Java 9 currently available and many people are learning/using it as well.
Some/most/all parts of Java 9 will most likely be around for Java 10 and Java 11 so you will be more prepared when those versions are released.
“The strongest of all warriors are these two — Time and Patience.” ― Leo Tolstoy, War and Peace