Right now Golem is the undisputed king of Rock. But if Tyranitar or Rhydon get a rock type quick move they might take the throne.
And there is also Armaldo in Gen 3 which has 222 base attack stat (golem has 211 base attack). If Armaldo get the same rock moves as Golem he might take the throne DPS wise but Armaldo has significantly less bulk.
So to anwser your question, yes probably still useful although it might lose the spot as "best" rock attacker