Same thing all numerologists will say: ah, something was wrong with the calculation. The world will actually end (insert some new date in the near future, so the grift can continue).

https://en.wikipedia.org/wiki/List_of_dates_predicted_for_apocalyptic_events

After his 1260 prediction failed, the followers of Joachim of Fiore rescheduled the end of the world to 1290 and then again to 1335.

History is full of this stuff :)