You deliver good value for just 2c!
I know that most members of the JDO (JSR12) Expert Group are reading this forum and we should have further input on this. However any alteration involving the JVM spec should be considered a long road to go down.
In the mean-time the PersistenceCapable interface is facilitating persistence hooks that execute very quickly for enhanced versions of classes, whilst having no impact on un-enhanced classes.
The domain object models and applications you persist with JDO today should be portable to future strategies of JDO implementation (VM hooks, "persistent" class modifier, etc.) when and if these arise.
And remember that enhanced classes are not enhanced in a vendor-specific manner, but the same enhanced bytecode can be used with alternative JDO implementations. On the whole I believe that JDO provides a sound and future-proof architecture for transparent persistence.
But that's my opinion. What do others think?
Kind regards, Robin.