I think you're probably right concerning domestic matters. Trump doesn't have the gravitas to get down in the weeds on most legislative issues, so he probably will defer to Congress, take the credit when it suits him and dodge when things go south. When it's all over, his domestic legacy will, for better or worse, probably look like that of your average Republican president.

The worry with him is foreign policy. Yes, world leaders are used to dealing with nut jobs, including some with nukes, but none of them lead the only remaining superpower and the nation that others look to to lead the western world. I don't think we should underestimate Trump's capacity for creating havoc with his undisciplined mouth or his propensity to put his own interests before those of the nation.

I also wouldn't be too sanguine about the Pentagon ignoring him. There could well be some situations where they simply can't. Inconvenient as it sometimes is, that Commander in Chief thing is real.