There is no guarantee that Apple will offer refurbs of the model you want after a machine is updated.
Though there is a chance that Apple will have some new "old stock" machines after an update as they finish clearing the channel.
So it's a little hard to say yes there will be a price drop AND machines available...
Since people do stop by to say there's a smoking deal on old model refurbs, only to see the availability vanish very quick.