I'm curious: when will D2 be declared stable?

[dsimcha]

== Quote from The Anh Tran (trtheanh at gmail.com)'s article
> In my limit knowledge, D2 has invariant+pure integrated already, to
> support functional paradigm. Is there any 'feature', cooking in
> backyard, so that d2 can't be declared stable?
> This is purely speculation:
> 1. Concurrent support?
> 2. Operator overhaul?
> 3. Add more paradigm??? :D
> 4. Something to assimilate Martian people? :D

Well, this _was_ supposed to happen in April of this year b/c that's when Andrei's
book was supposed to come out.  Whether that's still feasible, IDK.