Animals feature in some works on universalism but not many. However, they do give rise to some important and quite challenging questions.
To start with, do we know which animals, if any, are conscious? And, if consciousness is an attribute of the soul, does that not mean that animals have souls? If so, what will happen to their souls after death?
Leading on from this, if we conclude that some animals are conscious, but they don't have a future beyond this life, should we not ask why God did not design them to be unconscious biological machines instead? If animals' suffering does not lead to a good afterlife, would not doing that make God the cause of unnecessary suffering?
I think it is surely the ambition of God to restore all creation to a positive state, the bible often speaks of the reconciliation of all in heaven and on earth and the making of all things new, he is clearly aware of the needs of all creatures and capable of satisfying them all, so I cannot envision an outcome where God provides anything short of that for every sentient individual ultimately.
The assumption is that animals in their life already on earth rent already doing as God designed ? If we look at the tale in Genesis which speak of God love but also human arrogance and curiosity and corruptibility there is nothing that leads me to believe animals did anything to go against how God created them........
I'd wager any dog owners or lovers reading this would tell you those creatures embody the most fierce loyal unconditional love they just want to be with you and if thats in their character and God through evolution of the wolf has refined these creatures to embody such love, then Id suggest they are already with God. Of course animals as unthinking machines is an interesting one.
But to answer your in the new Earth and the New Creation I tend to think animals will of course be present as for which well all and I Imagine all means all past and present that is to say even extinct what that looks like I cannot say. Will the creation even be like this one?, will it even be corporeal or non corporeal big questions which can be theorized upon. But it where I go Apophatic in that I'm not going to know and thats fine I cannot hope to know fully in this life the infinity and omnipotence that is God I can only take assurance in Gods Love