If the WTBTS took 1934 as the new date they could even bring back in the 'generation' teaching.
Not with only 5 years left for the end of 80 years. They took damage with the first generational change. If they change 1914 to 1934, they'll lose more people. If they change back to the original generation teaching too, they'll lose even more. Then, with these changes fresh in their minds, if they drop the generation teaching again 5 years from now and go back to the way it is now, even more people will call BS.
It's too risky for the potential gain to be had from alarming people all over again.