There are several classes that I can see no need in making a 4th spec for.
People may want to bitch about how there are no spec trees now and no "full customization or multi-tree specs" now, but it's a moot point.
In old WoW, if you have WOW account and WOW money when we still had spec trees, if you wanted to be competitive, you used the exact same tree as the next guy. At the end of Lich King, if you were a hunter, you used the Survival spec that ElitistJerks posted, to the letter. No variances, except for maybe the choice of a teir 3 spec over another tier 3 spec, which was usually a vanity type thing rather than utility. Or it might be an anti-caster rather than general purpose, or whatever.
All Blizzard did was took these cookie cutter builds that everyone was using and made them "The Build", since anyone that was playing, whether casual or competitive, was doing those build anyway. They merely left us with the utility choices along the way.
I prefer this method from a cost-efficiency perspective: much cheaper to unlearn one spell in favor of another, than doing a full respec and then have to go back and look up the entire tree again to see where to spend all the points.