Congress is scared of the FBI, and they are scared of Rosenstein, no doubt about it. Hence the endless string of empty threats, and delays.
They want to look tough without being tough. Its safer that way for them. Better to put on a show than it is to take corrective actions, and run the risk of exposure to “unwanted consequences”.
I fear you are correct. We will need our own General Pinochet to cleanse the vast corruption. President Trump alone is not enough.