There have always been echoes of Hitler in some of the things Trump does and says.
In a specific sense there will never be another Hitler.
In a general sense there have been a few already and Trump might be one.
They both said that their country was in decline due to internationalism and feminism and emphasized a resurgence of patriotism and manliness.
They both blamed minorities for problems that had nothing to do with those minorities.
They both threatened to ban and jail their political opponents.

But out of the two, only Hitler promised to start a war, only Hitler ever jailed other political parties, only Hitler took over all labor unions and all schools and universities. Only Hitler ever organized a private partisan street army, and only Hitler ever revoked the citizenship of the minorities he hated.

Basically, Trump could easily try to do more of the things Hitler did, and it would, at that point, be a more accurate comparison.
It's not hard to imagine.

But it's already way too close for comfort.

---