Maybe they can prove that the parousia actually occurred in 1931, when God gave them a new name.This will allow them to return to the old understanding of "this generation", buying them more time.
When I explained to my very indoctrinated friend that Jerusalem absolutely did not fall in 607 BCE but 20 years later, and how that throws off the 2520 years, he went from a shocked face to a happy face and said they'll switch it to 1934 "to buy more time!"
Problem: It's 2017. If they wanted to do that to buy time and for the sake of accuracy, they really should have done it back in the 70s, 80s or even the 90s when it had been made clear to them that 607 is totally wrong.