Class E felony, up to 5 years in prison. (Though up to the discretion of the SS I think, sometimes they just pay you a nice visit).

For more detail: that's similar class as like bomb threats... Class E is closer to the mildest end of a felony.

Trump's speech is considered hate speech, because it attacks a group of people because of who/what they are. This is targeting a single person, and so isn't hate speech. But it is absolutely illegal, and absolutely should be investigated.

A threat and a federal crime?

Sedition, plain and simple.

It's not a joking matter to threaten the life of any individual, be they President or otherwise.