Since the Supreme Will planned that all the individual components of creation will ultimately attain good, it must be His purpose to bring the entire world to attain only good in the end. Just as He created punishments sufficient to bring each individual to receive good in the end, so He has the power to create a kind of punishment, or whatever else it may be, for the entire world, that is evil at first but ends up being good.
It is certainly true that His will is only for good, and this is what must endure forever. For His power is forever and only His will holds sway. If the means to accomplish this end is through evil, this does not undermine His intention to benefit everyone, for evil is the means to eventual good. On the contrary, His good purpose will eventually be revealed and the intended result will endure forever. For what comes out of the entire cycle on every side is only His essential goodness.