A couple of points to consider - animism is not pantheism, first of all, but the belief that all entities have a spirit, an “animating” force - hence the name.
Now that’s out of the way, pantheism is, broadly speaking, the belief that the earth, the universe, the whole shebang, so to speak, is an ultimately unified, divine entity. We are now well aware that the earth has not been around forever and will not be around forever, but as far as our ancestors were concerned, the earth, and what could be seen of the sky from the earth, might as well have been the totality of existence.
It doesn’t actually matter for the central concept of pantheism - that is, all that exists is part of the one divine whole - that particular entities within the universe will cease to exist as they are; any more than it matters that when we die, our bodies will decay and return to the elements of which they were composed. The universe itself - that is, the matter and energy of which the universe consists - as far as we can discern, has existed in some form and will exist in some form (though probably not the one we presently live in) always, literally from the beginning to the end of time and perhaps beyond. But that is getting into far more complex cosmological stuff than I readily comprehend. Time to go back and read Lawrence Krauss again…
Suffice to say that modern pantheism, sometimes called naturalistic pantheism, is a variety of monism which holds that all that exists is natural, and as such, we are all ultimately part of the same whole. Our bodies contain elements forged in the hearts of stars; the universe made us, sustains us, is us. It really doesn’t matter to the set of beliefs and attitudes attendant upon pantheism that the forms within the universe, from the tiniest atom to the immense red giant, to the vastest of galaxies, are not immutable - everything that exists now is part of the great dance of time and change.