Respectfully disagree with your first two paragraphs, I believe that the convictions and immunities being granted are all laying the groundwork for the bigger picture. Trump’s inner circle has been very sloppy with their stories and paper trails, frankly, because trump has been able to bully his opponents into submission historically. This sloppiness makes the job for Muellers team easier. These things take time, largely because of needing to get the ducks in a row with a high degree of precision, but I get the sense he’s closing in with so many of trumps people turning on him in recent weeks.
Related to your third paragraph, I agree that politics has become so divisive that we risk seeing this occur again. However, my belief is that the current state is so nasty that good lessons will be learned going forward and we won’t elect such an unqualified, antagonistic, narsissistic, corrupt bully and demagogue again any time soon. If you believe in any sense of karma, trump has brought much of this on himself. He didn’t have to conduct himself by constantly attacking, he could have acted with dignity and civility. Of course, that’s not who he is. But what goes around comes around and he’s going to get his.