The Democrats will still retain control of the Senate even if Herschel Walker, in spite of his innumerable personal weaknesses, somehow wins the runoff in December. Does that mean the runoff doesn’t matter?
No, for reasons that have more to do with 2024 than 2022. This time around, the playing field was tilted towards the Democrats, because the Republicans were defending a large majority of seats; in 2024, however, the Democrats will face challenges in Ohio, Montana, and West Virginia (yes, Manchin is still better than the alternative). As a result, if you were a betting man, you would put your money on GOP control of the Senate after the next election regardless of the outcome of the presidential race.
Having an extra seat in the Senate today will help after 2024. Even if the GOP has nominal control, Collins and Murkowski will still operate as swing voters for some purposes, so 49 seats wouldn’t be a disaster. Victory in Georgia would be a step in the right direction.