The biggest risk Sony has in this situation is that their manufacturing processes might get cheaper as time goes on, but if they have 1.9 million units sitting in warehouses they've already spent the money to build them at the earlier, higher cost. And storage is not free -- even if you own the warehouse outright, you're paying property taxes, utilities, labor to manage and secure the piles of unsold equipment... so they're not getting any cheaper.
This makes any kind of a retail price cut even more painful to contemplate, because any manufacturing savings may not actually have been realized by Sony. The backlog could even delay a price cut until the savings on NEW manufacturing can support it.
EDIT: What FishyJoe said much more succinctly while I was typing this up. :)