Try not to think of it as Trump will never be held accountable for his four years of crimes, but instead think of the fact that he will be completely unrestrained by any laws against the crimes he will commit if he gets elected again.
The telling line for that in the decision was that Congress can’t hold him accountable. While everyone is focusing on his upcoming trials (which have nothing to do with Congress), I am noticing that will pretty much preclude any further impeachments. One step closer to removing those pesky checks.