Is it normal for an advisor to expect >80 hour workweeks from PhD students, and threaten them with dismissal?
I'm sure some advisors do act this way.  I don't think it's very common, but it does happen.  It's more common for advisors to expect certain results than a particular hourly commitment, but all these things are a matter of extent.

However, in trying to figure out whether to switch advisors, I think you're asking yourself the wrong question.  The right question is: 


  What type of advising relationship works for you?


If you feel energized, motivated, and happy under your current conditions, that's one thing.  If you feel overburdened and miserable, then you should probably look for a different advisor.  Even the most competitive Ph.D. programs have faculty who are not so demanding.  You have to figure out what type of style works best for you and try to find an advisor who is a good match.