The beginning of my answer to your question may puzzle you initially, but I believe my answer would not be complete without reference to--and explanation of--the word, nihilo, which you seem to define as having non-existence or as having disappeared (i.e., being no longer apparent). First, some questions:
Is God eternal?
Was there was a "time" when all there was was God?
If your answer to the above two questions is yes, then would not a better expression for God's creative activity be "out of the fullness of His being" and not "ex nihilo" ("out of nothing")?
In other words, for all eternity (i.e., "past" eternity) the eternal I AM was all there was. The Father, Son, and Holy Spirit simply existed and had no need for anything visible. For all eternity, the Triune God--Father, Son, and Holy Spirit--enjoyed a loving relationship with each other before anything or anyone was created.
Additionally, we know that before anything came into being the Lamb of God was slain "from [or before] the foundation of the earth" (see Ephesians 1:4 and Revelation 13:18). The reality of "the Lamb of God who takes away the sin of the world" was a fait accompli from all eternity. In other words, its reality was just as real in eternity as it was in real time at Calvary's cross. Moreover, the salvation of humankind was not "Plan B"; rather, it was "Plan A," and the only plan in the mind of God from all eternity.
Put differently, there was no such thing as nothingness before the foundation of the earth. Only God existed before the foundation of the earth, and not nothing and God, but simply God.
From that perspective, the concepts of non-existence and nothingness take on new meaning, do they not?
As for whether or not God is able to--or choose to--make something or someone cease to be, I think my answer has to be no. Once something or someone comes into existence, it may take on another form, but it still exists. A rock, for example, when exposed to lava does not cease to be; rather, it takes on the characteristics of lava and becomes unidentifiable as a rock. The same could be said of a human when the spirit has flown. The body decomposes and eventually turns into dust. The living, breathing human being no longer exists, but its corporeal elements do, just in a different form. As God said to our first parents after they had disobeyed Him,
"By the sweat of your face
You will eat bread,
Till you return to the ground,
Because from it you were taken;
For you are dust,
And to dust
you shall return.”
In conclusion, the sin-wracked, polluted globe on which we live, over which God had appointed us stewards, will also be changed. God will not make all new things; rather, He will make all things new. God will replace the groaning-in-travail earth that we inherited when we fell from grace with new heavens and a new earth in which righteousness dwells for all eternity (Isaiah 65:17 and 2 Peter 3:13).
Come to think of it, the only thing that disappears is the believer's sin, which is washed away forever by the blood of the Lamb. In its place is the righteousness that comes by being in Christ Jesus:
Therefore if any man be in Christ, he is a new creature: old things
are passed away; behold, all things are become new (2 Corinthians 5:17