Much of your #14 is quite correct. But are you basing that statement on the results of the recent presidential election?
In my view the Dems have a lot to gain with the debate. Either JB flat out "wins" (extremely unlikely even with MSM help) or JB's performance will justify any subsequent replacement.
Trump will, we hope, also recognize that any question presented to him by JB or anything at all the MSM may utter directly or indirectly will likely be an intentional trap.
Best posture IMO is Trump, after checkmating JB on the facts, will treat him somewhat tenderly and convey a sense of sympathy to those who may be thinking of voting for JB.