One by one the GOP is picking off, like birds on a wire, every career public servant who could damage Trump. Sally Yates fired. Comey fired. Sessions publically humiliated into submission. McCabe fired with no objection from FBI chief Christopher Wray.
Rosenstein is next. The upcoming release of the phony memo written by the GOP staff of the House Judiciary Committee is being done explicitly to provide the rationale to fire deputy attorney general Ron Rosenstein.
After the Ken Starr disaster, Congress rewrote the special prosecutor law. Under that law, Mueller has to send his findings and recommendations not directly to Congress but to the attorney general, who then has to decide what to do with that report, including making it public or passing it along to Congress for action. Sessions has recused himself from the Russia investigation, so it is Rosenstein who will receive Mueller's recommendations and decide what do to about them. Without Rosenstein's support, the Mueller report won't see the light of day (legally) or lead to any action being taken against Trump.
Trump will soon fire Rosenstein based on the rigged House memo. No doubt he will fire Mueller too, but even if he doesn't all he has to do to bury Mueller's report is to find a new deputy attorney general who would be willing to do that. In a Washington full of Republicans who are willing to destroy the FBI and the DOJ in order to save Trump, that won't be very difficult.