Ideas for improving Jython
Most new work should target Jython 3.x (https://github.com/jython/jython3); or should have a plan to target both Jython 2.7.x and Jython 3.x.
CExtAPI support through JyNI
Continue work on supporting the C Extension API (http://jyni.org/), especially support for Windows.
Implement Python bytecode compiler
Rather than compiling to Java bytecode, emit Python bytecode instead. Note that it still may make sense to use $py.class output instead of .pyc, but that should be a packaging option.
Implement support for CFFI: https://cffi.readthedocs.io/. With recent support of large methods in Python via the use of CPython to do the compilation, we should be able
Port Jython grammar to Antlr 4 from Antlr 3
Such work should start by examining the grammar defined here, https://github.com/antlr/grammars-v4/tree/master/python3, and compare to https://github.com/jython/jython3/blob/master/grammar/Python.g It should also take account the variant to support partial parsing for console usage; as well as to continue to support the ast/_ast modules.
site-packages support in a singlejar deployment
Starting with http://bugs.jython.org/issue2143, develop a packaging solution for Lib/, including Lib/site-packages, that works with a Zip Filesystem Provider. Such a solution needs to be compatible with all filesystem usage, including being able to introspect metadata at the file level.
Implement asyncio support for Jython 3
Such work should target Netty for maximum performance, instead of the current socket/select/ssl emulation, which also layers on Netty.
Support MyPy for Java types
It should be possible for MyPy to typecheck Jython code, including the use of imported Java types.
Other ideas for Jython 3?
Please add them here by submitting a PR.