It is not likely that Pope Francis will "demand (an) oath of 'fidelity' to himself". Firstly, it would be stupid for a number of reasons and Francis is not stupid. Furthermore, the 1989 Profession of Faith already requires an oath of unconditional submission of the mind and will to the "authentic magisterium." The "authentic magisterium" is essentially a synonym for the person of the pope. The recent declaration that Amoris Laetitia is an act of the "authentic magisterium" is an appeal for unconditional submission of the "mind and will." All Francis needs to do is demand every cleric who holds any position of jurisdiction in the Church keep the oath they have already taken. And since none that I know of hold Dogma as the proximate Rule of Faith, they will submit.