While looking into the effort necessary update our EHCache Extension to 3.3 (atm 2.4), i learned that EHCache support the Java Caching interface, so maybe it makes sense to make an abstract implementation for Java Caching and then the EHCache implementation only has to extend this implementation with everything specific to EHCache, for example the configuration.
Java Caching is supported atm by the following caches:
https://jcp.org/aboutJava/communityprocess/implementations/jsr107/index.html
So adding new caches will be a lot easier in the future if they support Java Caching.