Rashi: Some say so. This is primary, for it says "Ki cha'Asher ha'Shamayim ha'Chadashim..." (66:22). Radak citing Ibn Ezra - the firmament will be new, Hashem will make a new good air, so people's bodies will be healthy and live many years ¹ . He will add strength to the land - it will be new.

Radak: No. Amidst the great good, it will be as if the world is new, i.e. new Shamayim and Eretz - "v'Lo Sizacharnah ha'Rishonos" (the first afflictions will be forgotten).

Radak (66:22): No. They are called new, for they are fresh like the day they were created; they did not wither. Only things of the land wear out. It says "Dor Holech v'Dor Ba veha'Aretz l'Olam Omades" (Koheles 1:4).

Malbim: Yes. Shamayim and Eretz found now were created to conform with nature. There cannot be constant good without bad. All physical substance changes form; it does not remain fixed; there must be a lack. Similarly, all the mixtures via motion of Shamayim, some bad must be found in them. However, then their substance will have a different nature, without any bad or lack at all.

Malbim: People will not be able to picture to themselves lack, death or bad at all. It will not be the nature of the existence, due to the increase of good and success.