Let us rightly divide the Word of God concerning angels and man.
ANGELS ARE SPIRITS
4Who maketh his angels spirits; his ministers a flaming fire:
Hebrews 1:7 And of the angels he saith, Who maketh his angels spirits, and his ministers a flame of fire.
Are they not all ministering spirits, sent forth to minister for them who shall be heirs of salvation?
Behold my hands and my feet, that it is I myself: handle me, and see; for a spirit hath not flesh and bones, as ye see me have.
MAN IS BODY, SOUL, AND SPIRIT
1 Thessalonians 5:23 – And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ.
Matthew 10:28 – And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell.
Hebrews 4:12 – For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart.
Matthew 16:26 – For what is a man profited, if he shall gain the whole world, and lose his own soul? or what shall a man give in exchange for his soul?
So we see that angels are spirit, but man is body, soul, and spirit.
The soul and spirit are closely knit together but the Word of God can divide/separate the two.
Now read the following verse.
Then shall the dust return to the earth as it was: and the spirit shall return unto God who gave it.
We read here that our bodies will return to the dust from which it was created, but our spirit will return to God from where it came from. Above earlier we read that the soul is what is judged either going to everlasting life with the Father through Christ Jesus or in everlasting torment where there is NO ANNIHILATION! Death is thrown into the lake of fire as well, the second death does not mean annihilation and the lake of fire is not a purification process. If it were so then Calvary did not need to take place.
Now with that said, angels cannot cease to exist. Why? Because they are created spirit beings and they came from God. (The spirit returns to God from whence it came.) That is why our spirits will return to God, but fallen angels are locked up waiting the judgment. No part of God can die, did you hear that? No part of God can die!
That is why the Heavenly Seed had to be born of a woman in the flesh and be body, soul, and spirit as we are.
This is why God did not destroy Satan after the fall. Satan and the fallen angels are spirit and they cannot die or cease to exist but they will be in torment along side those who refuse accept Jesus Christ of Nazareth as their LORD and Savior.