“Mueller will get Don Jr. Indicted forcing Trump to pre-pardon him. BAM! Obstruction of Justice.”
One, the President cannot obstruct justice by pardoning someone according to his constitutional powers. Two, he cannot obstruct Mueller. He is Muellers boss. He can fire him tomorrow if he decides to. The President has the unquestioned power to direct an investigation to be started , or stopped, or to undo one with pardon power.
Trump cannot obstruct Mueller by supervising him.
What Trump can or cannot do per the Constitution has nothing to do with the democrats. It will simply be an excuse. And Trump will be fighting impeachment during his campaign for reelection. I believe that’s their plan. I also believe Mueller is keeping the Deep State informed.