John Gill Commentary Hebrews 1:11

"They shall perish; but thou continuest: And they all shall wax old as doth a garment;" — Hebrews 1:11 (ASV)

They shall perish
That is, the heavens and the earth; not as to the substance of them, but as to the quality of them; the present form and fashion of them shall pass away; the curse will be removed from them, and they will be renewed and purified, but the substance of them will continue; otherwise there would be no place, either for the righteous or the wicked,

But thou remainest ;
without any change or alteration, neither in his natures, divine or human, as God or man, nor in his office as Mediator; as a priest, he has an unchangeable priesthood, and ever lives to make intercession; as a King, his kingdom is an everlasting one, and of it there will be no end; and as a prophet, he will be the everlasting light, of his people.

They all shall wax old as doth a garment ;
garments in time wax old, and lose their beauty and usefulness, unless when a miracle is wrought, as in the case of the children of Israel in the wilderness. Now the heavens, and the light thereof, are as a garment and a curtain, (Psalms 104:2) and these, together with the earth, will in time come to their end of usefulness, in the present form of them; see (Isaiah 51:6) .