What are the list of things that prevent Rakudo-on-whatever being labelled as a full fledged production release?
There'll likely be as many very different answers to that as answerers.
For one definition of "full fledged production release" that I think is arguably reasonable, the main missing absolute essentials are completed documentation and user support. I think aiming at producing such a release in the next few months would be a big waste of everyone's time.
Maybe you mean "like P5". That might never happen; you only get a QA level like P5's if you get an adoption level like P5's.
Extrapolating on the plans and progress of the last 2 years, and assuming no bus accidents, I can see the P6 team aiming at having a solid 6.0.0 beta that adds p5interop, compact arrays, concurrency, async IO, unicode, macros, module versioning, better libs, better module installer, much better performance, complete documentation, and user support by YAPC::NA 2014.
(In case anyone misinterprets this as promising big things or somesuch, this is not a promise but rather a list of the main things I think will be added between now and shipping a "full fledged production release".)
Update: P6ers showed pretty much zero interest in focusing on a 6.0.0 until very recently, a year later than I thought they might take aim, and they haven't said what date they will aim at, if any. But P6ers are now talking seriously about 6.0.0. I still think my list of things that P6ers will want to do before 6.0.0 remains about right. p5interop, concurrency, async IO, and a better module installer have arrived. Module versioning, libs, macros, performance, and doc have all improved but remain very much works in progress. Finally, work has barely begun on compact arrays and NFG (the key to P6's full approach to Unicode) but I still expect them to be part of anything officially called 6.0.0.