Just to be clear: US Attorneys, and a Special Counsel, have to get approval from DOJ hierarchy and a federal judge to grant formal immunity.
There can be informal deals that might fall under prosecutorial discretion, but that seems unlikely in such a high profile case.
I believe bloggers are making stuff up and FReepers are hyperventilating.
Who's to say that hasn't happened? Remember, Sessions has recused himself so only Rosenstein and a judge is needed. Any judge in the Swamp would easily do that, and also keep it quiet.