Ok that answers my question. So after he leaves office he could still be prosecuted for it.
In theory anybody can be prosecuted for treason at any time.
He won’t be prosecuted for anything, because we’re not dealing with theory.
Prosecutorial discretion means that any prosecutor can decline to prosecute, for whatever reason.
The GOP will not allow a prosecution of Obama to go forward.
They will decline to prosecute him whether it be for criminality/corruption, or for treason or anything else.
The smoking gun would be if they can uncover proof he supplied weapons to radical muzzies, then the government should pursue charges of TREASON. In the very least, all pension, benefits, SS protection, etc. should be revoked. Granting immunity to the 'Beast may be the easiest way to get the evidence needed to put him in Gitmo.