Yes. If Trump took punitive action, it would be a Saturday Night Massacre scenario. Plus Trump probably only knew a fraction of the truth and needed to let things play out to see the full conspiracy. Better to let the Rats involved lie their way into a corner.
Trump will eventually have to fire Rosenstein. Rosenstein will not leave on his own, no matter how many embarrassing things they find on Rosenstein. And the Senate would never vote by a two-thirds margin to remove Rosenstein.
When the House demonstrates a successful impeachment vote against Rosenstein, Trump can then fire him.
Surprising numbers of people with a tin ear for the politics of firings. The Comey firing was a necessary evil and Comey had already planted his (potentially classified) notes to hit back. The rest of the bunch are not worth spitting on, much less firing. They are doing nothing to stop MAGA, they are doing nothing other than putting Manafort in jail (not sure what Manafort did to deserve jail, but his prior work for foreign governments was the precursor). Flynn will clearly be pardoned if the charges aren't dropped. 13 Russian trolls? LOL, who cares about them, they are irrelevant. Papadop will get a slap on the wrist and a hot Italian wife, he was an idiot anyway.
And indeed, the longer we have waited, the weaker Mueller's case has become. Also still tons of time before the elections.