Rosenstein would be in charge. He is Deep State. He would continue to keep things covered up. That's what he does.
So far, Trump has been a pleasant surprise, even beyond my very high expectations.
There is indeed a deep state, and for decades, the coverups have been accommodated and even directed from the highest level (POTUS). It remains to be seen how the deep state will fare against this POTUS.
It’s one thing for a SOS, AG, Deputy AG, or FBI Director to engage in rampant corruption and coverups, knowing the POTUS is fully in the loop, on board and has your back, as with the Obama administration.
It’s another thing entirely, knowing the POTUS and most of his team are genuinely determined to hunt you down and drain the swamp. The Deputy AG and many others no doubt have a lot they desperately need to cover up - but the day Hillary failed to win the White House, their coverup began to unravel.
Trump can’t and shouldn’t engage in anything that appears like a political witch hunt, purge, enemies list, etc. or public support for draining the swamp would vanish overnight.
Trump can’t be the one to kill the deep state, it has to die of natural causes, from lack of sustenance. It takes time and patience. Trump won’t get to take credit as some great dragonslayer. Conservatives won’t necessarily get the satisfaction of watching crooked democrats perp walked in orange jump suits. Trump supporters like you and I will not necessarily get our moment of vindication and be able to say “See? I told you so”. But without a POTUS providing cover for the deep state, the swamp will drain - slower than we’d like, and with less fanfare, but it will drain.
Clearly, I am more optimistic than you.