If they can get rid of the generation of 1914, the close of the call to the remnant in 1935, the banning of blood proucts in medicine (except for the big four parts) the Tuesday group study and cups of tea at Assemblies, there is nothing that they cannot change.
Consider, I usd to believe that the end of this world would come within a lifetime of the first World War, why? because Jesus told me (in Mathew 24) That, I believed, was from the Master's mouth..Then I suddenly did not believe it anymore because some unknown man in New York wrote an article that I did not understand, but told me that I had been wrong. So I changed my belief in direct denial of what I read in The Bible.(That is if you still accepted the rest of the Witness teaching)
I changed to follow an organization..People just follow an organization.They believe what it teaches. Doctrine changes only faze a few old ones who cannot grasp them , the rest just say, "Ok" and get on with it