WT'ism has the potential to become more and more fanatical.
But it would take a while to reach the heights fanatical mahometans are attaining lately in the news.
The history of Mahomet's followers is filled with the ebb and flow of fanatics, just like the history of Christendom is also filled with maniacal fanatics who kill, persecute and maim. (e.g. Crusades, Dark Ages Europe, pogroms, ethnic cleansing by anti-hereticals, by the Catholic Inquisition, yes, and also fanatical Orthodox and Protestants alike burning people at the stake).
And of course, there's the WT's lamenting that today there's no stoning of apostates.