I think talk of Comey taking Trump down is likely premature.

While support for Donald's impeachment is at an all time high -- 43% compared to an approval rating of 36% -- that process is long and tortuous.  The House needs a majority, then the Senate must hold a trial -- and a 2/3 majority is needed in the Senate.  

Donald won't resign -- the only time he ever gives up a fight is when he can line his own pocket (see his many bankruptcies) -- so going down is likely not in the cards.

However, Comey will further damage his credibility.  More Republicans will abandon him, and even some of his willfully ignorant supporters will finally see that it isn't fake news after all.  This could have the effect of making him a lame duck less than a year into his term.  Not so terriffic for stability or getting things done -- but at this point, I would rather have a United States that does nothing than one that follows Trump's script.