I just got off the phone with CC and have been told that T-Mobile has now been officially told (by whom I don't know) that the device is on backorder, AND that
the backorder is 4 days. I've been instructed to add 4 days to the original arrival estimate. In my case, that would mean the phone would arrive on Thursday.
Given all that's happened, I'm not going to hold my breath, but... it's good that they're finally saying
something.