A possible POD here might have been around 1400, with a longer living Timur, who destroyed the Ottomans sufficiently to stop them from rebuilding their empire. If we assume that an ATL reformation had been attempted at about the same time as in OTL, that in the first half of the 1500s, what would its chances of success have been? I assume here that no similar threat like the Ottomans would have arisen. The existence of teh Ottoman Empire meant that the Habsburgs had to put its main focus on fighting them rather than the protestants. Without the Ottomans, they could have used all their power against the reformers.