The impending doom of Hurricane Irma (not the last catastrophic hurricane of the 2017 season I fear) is sobering Trump up.

Cannot lead in the face of abject misery caused by weather, through bombast and jerkishness.

The bombast and jerkishness was totally backfiring on him anyway.

Moderating himself makes eminent sense politically.  He becomes a more effective President, and history treats him kinder.  

The problem is that he's still a Narcissist.  So, whatever progress he makes as a leader by this current move, which will increase and last for the short-term foreseeable future, is always at risk of just imploding.

America's big mistake, and specifically the mistake of liberals/progressives/Democrats, would be to get too far into bed with Trump.  He's a pretty ill individual.   His decisions are governed by that illness.  

He still needs to be removed by Congress, even if he starts acting moderate.  The focus has to be on the danger of him having the nuclear football.