not really. the hardest thing about designing a class is not the specs themselves, but the class as a whole and it's niches. what makes this class unique? what are the movement skills? et cetera.
with 4th specs, you have all of that already done. you just need some fine tunning.
in fact, 4 specs is so easy that you can just take an existing spec, copy paste it, adapt the copy to do something else and call it a new spec. it worked with feral/guardian.
you could take arcane and make a "time" healing spec from it.
you could take demonology and make a "demon hunting" tank spec from it.
you could take beast mastery and make a beast wrestling melee dps from it.
and so on