There is much debate about the Roman position vis a vis the Germans after the Teutoburg massacre. Many have taken the position that the loss of the three legions blocked forever Roman attempts to conquer Germany influencing the course of European development for the future. I think that point is debatable for at least two reasons. First, Tiberius ended the German campaigns because he felt the effort was not worth the losses incurred, not because of the massacre. He decided that the plan of letting the German tribes fight among themselves was a better strategy. Second, he had better uses of the army than post them in barbarian Germany.
The fact that Rome never conquered Germany was more about the difficulty of accomplishing that goal given the strength and relationship between the German tribes than anything else. Rome would eventually reach Britain during the time of Claudius, but would never move east of Gaul after 16 A.D.