Hypothetical, not that this would happen, but let's consider the following.
If you were given the choice to vote on Blizzard's website, if you wanted a new class OR to have one spec added to only three of any of the currently existing classes (minus druid). Resulting in 3 pre-existing classes gaining a fourth spec.
Which would you choose?
What Specs would you hope for?
What class would you want?
(I figure since a new class has 3 specs, it would be sorta similar adding one spec to 3 existing classes)