dave-in-nj:
I don't know how you can hang on a trapeze cut the wire you're hanging on and run a new wire all at the same time
I would look at having two ESPs
one downloads the program that you want to upload then it would reprogram the second oneSounds like a waste of an extra processor but that way you would have one live programming the other one
the esp8266 should flash a connected Arduino. so here are two mcu.
but the esp8266 can update itself. see Updater class, ArduinoOTA, ESP8266httpUpdate or ESP8266HTTPUpdateServer libraries