According to Wikipedia, the Governing Body was officially established in 1971. That would mean, according to the dates given for years served, the original GB (1.0) would have been initially comprised of Fred Franz, George Gangas, John O. Groh, Milton G. Henschel, William K. Jackson, Nathan H. Knorr, Grant Suiter, Thomas J. Sullivan, Lyman A. Swingle, Ray Franz, and Leo K. Greenlees.
Now, if you consider GB 2.0 to be those who were appointed AFTER all those fellows passed away (minus Ray, who was kicked out in 1980, and Greenlees in 1984), then technically only Jackson and Morris would qualify for 2.0 since they were the only ones appointed after 2003, which was when Henschel died. As Henschel was the last WT President who was also a GB member, this actually seems fitting. I still don't know enough about Morris and Jackson to make any kind of call as to whether they might be able to finally bring a measure of meaningful reform to the org, but judging by the WT's actions since their appointment in 2005 prospects do not look particularly bright.
So, then, 1971-2003 being a period of 32 years, and GB 2.0 officially beginning in 2005 with Morris and Jackson according to the above criteria, it could well be another 3 to 4 decades before GB 2.0 is gone.
I don't think there will be a GB 3.0 as long as the current mentality continues to prevail. GB 3.0 won't have much left to govern.