Michael Flynn's guilty plea and agreement to cooperate with Bob Mueller's investigation was without doubt terrible news for President Trump and his inner circle: Flynn knows more than anyone about their dealings with Russia.

But, but, but: This doesn't necessarily mean Trump is in personal legal jeopardy, much less on the road to impeachment.

The atmosphere of hysteria is dangerous. We saw this yesterday when ABC News reported that Flynn planned to testify that he was directed by then-candidate Trump to make contact with the Russians. That sure didn't sound true. Hours later, ABC significantly softened its report, saying one source says Trump asked Flynn to contact the Russians during the transition about fighting ISIS. Huge difference.

Jeffrey Toobin, writing about Trump's lawyers ("The Russia Portfolio") in the forthcoming issue of The New Yorker, offers a gut check on how hard it will be to go after Trump, even with Flynn's help:"

• In several conversations with me, [Trump lawyer Jay] Sekulow emphasized that collusion between the Trump campaign and Russia, even if it did take place, wouldn't be illegal."
• Sekulow: "For something to be a crime, there has to be a statute that you claim is being violated ... There is not a statute that refers to criminal collusion. There is no crime of collusion."

Toobin points to two ways Mueller could move, both difficult:

• The Trump campaign received unlawful in-kind political contributions in the form of damaging info on Hillary Clinton.
• The Trump campaign aided and abetted the hacking of the Clinton-related e-emails.
• Toobin: "Nonetheless, based on the available evidence, both of these theories of criminal liability ... look like long shots for Mueller. Prosecutors tend to be cautious about pursuing criminal cases based on novel legal theories.

"This is why several White House officials worry most about a possible cover-up. Obstruction of justice is easier to prove. Remember: There's a reason Steve Bannon said the firing of James Comey will go down as the dumbest political decision in America history.

• Toobin: "In sum, on the basis of the publicly available evidence, the case against Trump for obstruction of justice is more than plausible. Most perilously for the President, Flynn may know what Trump has to hide."
• Go deeper: Jeffrey Toobin, "Ty Cobb, John Dowd, and Jay Sekulow are setting out to prove that there is no such crime as collusion."