Trump has no down side. He is being 100% sabatoged. What more can they do if he fires Comey?
By going after Trump 100%, they have put him in a position where he is free to do whatever he wants because there are no further consequences he can suffer.
This is the downside with going all in against a guy. You lose all leverage for the future and empower him to go nuclear against you because you have already shot your wad.
It does not matter how it looks of Trump fired Comey. There is nothing left the Democrats or media or leakers can throw at him they already haven’t.
If he fires comey he gets McCabe.