I feel that Arminius' position in the Cherusci/German alliance would still be up in the air, even following another decisive victory against the Romans. While the Germanic tribes valued heroic deeds achieved in battle, they valued their own independence and liberty even more. It's difficult to see how Arminius would be able to further consolidate the alliance into a proper confederation, seeing how fears of this occurring directly lead to his assassination OTL. Yet perhaps some quick political maneuvering on his part could outwit his in-laws/tribal opponents.
As for Roman political life, the death of Germanicus, as well as the loss of another 3-4 legions, would be a colossal blow to Rome's prestige. The psychological trauma of losing even more legions to that gods-forsaken land would make it political suicide to push for even more retaliations. Compound the threat of even more rebellions in recently-conquered Dacia, and you have a political shitstorm brewing.