You see, both the Keynesian revolution and the classical counterrevolution had one great virtue for ambitious academics: they involved both new ideas and more elaborate math than their predecessors. (It’s often forgotten, but Keynesian economics and the Samuelsonian modeling revolution went hand in hand.) New Old Keynesian economics, on the other hand, involves turning away from hard math back toward rough-and-ready assumptions based on empirical observation. Aspiring up-and-coming economists may be able to publish empirical papers in this vein, but theoretical analyses are likely to be met with giggles and whispers. Just because the stuff works doesn’t mean that it will be publishable.
So I think we’re in for a long siege in which the economics that works remains virtually absent from economic journals (except policy journals like Brookings Papers) and largely untaught in graduate programs.
Which makes sense, since economics thinking underpins a lot of our current school reform (that and pension theft).