Don't be too sure of that. Pope Benedict resigned presumably on account of opposition in the Vatican. Whilst Pope Francis is a tougher proposition, how long can he endure the constant overt criticism of him which is really unprecedented in modern times?
The opposition may appear to be small but how many are secretly behind it. The short shrift with which Francis has dealt with Cardinals Burke, Cañizares, Müller and Sarah must have struck fear in many members of the Curia and among bishops throughout the world. Perhaps the hierarchy are waiting to see which way the cookie crumbles, a cowardly stance when you think about it.
When the walls start to fall in on him Pope Francis may opt for the way out his predecessor opened for him.
Were he to do so, I can't imagine the College of Cardinals will make the same mistake again.