Just read a great article by Oliver Crisp (Fuller Seminary) for a version of the “incarnation anyway” argument, i.e. even if Adam and Eve had not sinned, the incarnation would have happened.
The aim of this paper has been to commend one particular incarnation-anyway argument, namely, the christological union account. If the christological union account is on target, then union withGod – a fundamental aim of creation – is not merely a matter of redemption from sin. It is about the need for some divine action of accommodation and condescension by means of which humanity and divinity are cojoined, in order that we may access the divine, and participate in the life of God. Although for all we know God could bring this about by some other means, it is fitting that this action be brought about by the incarnation, and, given the structure of the argument, this makes the incarnation independent of the fact of human sin… I submit that this unitive account provicdes a theological motivation for one version of incarnation anyway argument that has much to commend it. After all, it would be odd to think that the spectacular work of divien grace that is the incarnation is merely God’s rescue plan, rather than the outcome he intended independent of human sin in order to unite us to Godself.
Oliver D. Crisp, “Incarnation without the Fall,” JRT 10.3 (2016): 215-33.