Just my personal opinion but I feel people use the word "Bottleneck" far too often. Chances are you would see improved performance if you had a newer set up along with the 280X but the majority of that would probably be due to games utilising the better cpu etc. rather than "Bottlenecking". That said, newer chips do come with improvements PCIE 3 etc. from the gpu standpoint so I guess there's that to consider.
Also you clearly haven't watched TTL's video yet because saying you'll pick up a 280X when the 7970Ghz editions will probably be far cheaper is madness.