Newsweek interviewed Frank J. Fahrenkopf, of the Presidential Debates Commission, says we will know by noon. (but didn’t indicate which time zone.. lol)
If Sen McCain does not show up, then the debate cannot continue as it will be viewed as an illegal campaign contribution.
See the interview here. http://video.newsweek.com/#?c=40211&l=1785302026&t=1816384054