During the 80s the Sixers, Celts, Lakers, Rockets, and Pistons made the Finals.
The Mavericks also came within 1 game of making the Finals in 88.
When was the last time the same two teams made the Finals three years in a row?
When was the last time the same teams made the Finals four years in a row? Five years?
It's not hard to imagine the Warriors and Cavs going at this for at least another two years.