This is much to do about nothing. First of all I do not believe Josh will leave this year or in the near future. While the Redskins job is one of the best in the league, under its current set up it would be a disaster for a first time HC of Josh's age.
The owner is feast or famine. He will support your team with money, but wants instant gratification.
The fact that most of the key assistant jobs are already in place, could make that job untenable.
THAT BEING SAID, I think it would be a great experience for McDaniel to go down after the season and go through the interview PROCESS. It will not only give him a chance to see how NOT to run a franchise, but it will do him will to go through the process, and make his NEXT, more serious forray into getting a HCing job, that much more effective.