Very minor update.
1) A couple days ago, after about two weeks, I got an automated notice from the DOT that my complaint had been received.
2) I haven't gotten notice that the temporary chargeback was converted to permanent, after about three weeks.
3) As of today, the trip was still ticketed and confirmed (with the poor alternate schedule they offered and I did not accept).
4) The first flight is supposed to depart LAX tonight. I've been getting AM and DL notifications on it (change of gate, etc).