Good point. If she argues that the new language of the statute only allows the appointees a term of 6 years then this is her last term. She or others cannot be reapointed if they served over 6 years under new law.
Second, since the law also requires that terms be staggered, and accepting Ms. Berry's interpretation would undermine that requirement, the courts will look at the legislative history to determine the intent of Congress. Unless they can find clear evidence that Congress intended to allow 6 years terms, regardless of when the people were appointed, Berry will lose. Otherwise, a president could have all the commission members resign a month before he leaves office, then re-appoint them all to a new 6-year term, preventing the next president from having any appointments to the commission at all...