As of today, the flight appears to be automatically rebooked for IAD-MIA, MIA-LIM, without me even calling. The departure changed 4 hours (late 7pm from 11 pm originally, with a 4 or 5 hour layover in MIA to a LA operated flight to LIM).
Also, LATAM's confirmation comes from Twitter....
https://mobile.twitter.com/TheForwar...98233037524998
I called t and the agent didn't know that the LA flight was cancelled, as she saw it being there, but completely full. I asked her if there were any chances of being bumped to a later IAD MIA flight, but she said that was the last one. Also asked if IAD and DCA were considered co-terminals, as this was an involuntary change and maybe there was a chance of catching a later DCA-MIA flight, she said no, no way. If someone has better luck, please let me know.