Malachy says at least two more popes to go: Glory of the Olives and Peter the Roman. (Contrary to some perversions of the prophecies, Peter the Roman will be a great Pope.) And of course, nothing about St. Malacy's list says it is exhaustive.
In fact, St. Malachy's list also has an ellipsis (.....) between Glory of the Olive and Peter the Roman aka Peter the Omega. The ellipsis suggests an indeterminate number of popes between Glory of the Olive and Peter the Roman and that there will be at the very least one.