I'm going with now. Here's why.
Here's the Constitution on what treason is:
Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court.
The first sentence has the form:
Treason consists of A or B.
A = "in levying War against them [the United States]"
B = "in adhering to their Enemies, giving them Aid and Comfort."
Here is my take on A:
An occupation by military to force them to overturn a legitimate election is an act of war against the persons. Doing so in several states so it effects the outcome of the whole election is an act of war against the United States.
The word "levy" itself does not even require occupation, but instead can minimally require preparation such as arming a National Guard and sending them orders for occupation. That itself would be levying war.
So, if Trump, followed through with the suggestion from Flynn by merely sending orders that would meet the criteria of A. Thus, it would in that case be Twitler committed treason and those persons with him by providing aid and comfort (B) such as Sydney Powell and Flynn would also be treasonous.
However, Trump did not follow through (yet?). So now, Flynn and Powell are probably guilty of conspiracy to commit treason, but no one is going to call them on this, save some people on the Internets, like us.
Here is my take on B:
As above, if Trump initiated an act of war against several states by sending in forces to redo an election which he lost, he'd be the Enemy, in this case a domestic enemy. Flynn and Powell would be adhering to his will to be an enemy and providing aid and comfort in the form of advise and presumably direction of underlings, if any.
However, if there is no martial law in those several states or no occupation to force a reelection, can we still call Trump an Enemy in the sense of the Constitution? If we could, it would appear that Flynn and Powell would be treasonous and so all we have left to prove is that Trump was an Enemy of the United States at the time of the meeting where a conspiracy to commit treason was discussed.
Is Trump an Enemy of the United States?
The short answer is yes.
The longer answer is that just like the framers had built up a list of grievances against King George in order to declare their independence, one could do the same against Trump. His negligence and abuse have resulted in hundreds of thousands dead. The complicated issue of being a terrible President distinguished from an Enemy of the United States probably always lingers in the background, which is why it may be important to also point out the following:
It's really Trump's undemocratic actions that make him an enemy of the Constitution and the United States. Since the election results have become clear, he's controlled a faction of undemocratic persons ordering them to fabricate evidence of fraud by his opponent. He's engaged in phone calls and communications to several states to try to convince them to overturn results in order to take illegitimate control of the future United States, ie. an attempted illegitimate coup d'etat of statesmen and propagandists. The victim is the people and the future United States administration as well as a military that would be controlled by someone who didn't win the democratic election.
What is more than that is he has prepared a paramilitary of brainwashed minions, both Qanon conspiracy theorists and Proud Boys, the latter of which he told to "Stand Back and Stand By." These are persons he knows are armed and willing to commit violence on his behalf. There is a distinction here: he did not tell them to Stand Down but instead to Stand By...i.e. to be used in the future, which means he has prepared an army for future war.
Even though I think we all know these are the reasons that Donald Trump is an Enemy of the United States, we also know it would not get anywhere in a court of law. There'd be too much difficulty in proving his connections to ordering things (versus, say, Steve Bannon). It would also come across as free speech as opposed to conspiracy to commit treason.
If and when something more material happens, the conclusion in a court of law could be different.