Based on past performance, you won't see further price drops on the 3880 until it's discontinued and replaced by a new model. Epson always announces new 38xx series printers in late summer with delivery around the first of the year. So a replacement for the 3880 might happen in a year or so. Or, maybe not based on the 3880 popularity.
Well, here in Oz, ink refills for the 3880/3800 have dropped by around 20% and for as long as I can remember Epson don't often discount the 3880 models here much, recently they were offering a $200.00 discount for the 3880.
On top of that, OP's have commented on the difficulty in getting immediate delivery of various Epson printers (eg. 7980) in the US, all of which leads me to think they are getting ready for a release of new models and possibly new ink formulations early in the new year, we'll see...