There's still work left to do. In terms of next steps, there's still rdar://problem/22126141, which covers removing the 'workaround' overloads for print (that prevent bogus overload resolution failures), as well as providing a decent diagnostic when users invoke print with 'appendNewline'.
Swift SVN r30976
It is replaced by debugPrint() family of functions, that are called by REPL.
There is a regression in printing types that don't conform to Printable, this
is tracked by rdar://16898708
Swift SVN r18006
Alter CalleeSource and Callee to keep their own internal vector of substitutions and concatentate multiple SpecializationExpr substitutions. Update EmitPolymorphicArguments::emit to emit arguments out of the substitution list based on the generic parameters of the current function type instead of assuming that the substitution list and generic parameter list match up.
Swift SVN r3937