Have you seen the status update?
https://www.youtube.com/watch?v=Tc9vs_HFHVo&list=PLX8CzqL3Ar...
They will change the constant pool to have some kind of template information that gets specialized (what they call type species) into a specific set of types.
The plan is even if Java cannot fully take advantage of all possibilities due to backwards compatibility with existing libraries in binary format, the JVM will support it for other languages not tied to Java semantics and backwards compatibility.
I think you mean specialized generics (i.e. no autoboxing of primitives when used in generics)? Reified generics implies carrying around all generic type information at runtime, which will not be the case and also has nothing to do with performance. Non-value generics will still be erased I thought.