JSR-333 adds a number of features and improvements to JSR-283. Anyone still using JCR 1.0 or JCR 2.0 should be able to successfully rebuild with JCR 2.1 without making any mandatory changes. (IIRC, there are a few more deprecations in JCR 2.1, but none of the deprecated methods in JCR 2.0 have been removed.)
As of early October, the final specification for JSR-333 has not yet been adopted/approved, though the plan is to have that done before the end of 2013. This should still be compatible with our timeframe.