Do you mind sharing what it is that you've seen so far that is the basis for this conclusion?
Sales of the RT have been relatively sluggish against other tablets. The Pro will be competing with a wide range of Win8 capable notebooks and ultrabooks and its specs don't really offer much of an advantage over, say, Dell's or Lenovo's offerings in that range.
For those reasons, I doubt the Pro will be a big seller. But they will sell some -- Microsoft has it's share of "fanboys" too, who will jump at it. It seems a capable enough machine (battery life questions aside) so some people will choose it over other offerings.
Just a prediction, and as I noted upthread, predictions about the tech industry aren't necessarily reliable, historically speaking.