Who will take over Brazil's biggest ever corruption case? Who know, but one thing is for sure. Who ever it happens to be better hire someone to start his car every morning. No one, especially someone in law enforcement and criminal justice, should ever underestimate the will of criminals that have immense financial backing. This is some scary stuff.
From my very small knowledge of the event, it appears that the Supreme Court was unprepared to face this problem of who will inherit Zavascki's case. But seeing as this is a huge endeavor, Zavascki will no doubt have worked with others on this case, and there will likely be a suitable candidate who will take over with the same diligence.
Yes, it is unfortunate and downright tragic that Brazil's supreme court judge perished in a plane crash. But there are other judges, and one of them will take over this particular case. The probe will not end. It will continue under hopefully good hands. Such a huge corruption case will continue to receive priority.
There is no accountability for people at the highest levels of government. Everyone knows that they live by different rules than the rest of us. This is as true in Brazil as it is in the United States. No one will ever be held accountable because people in power are happy to abuse that power.