The word "nature" in its true sense, as applied to creatures, or beings, signifies the kind of organism and sphere of existence in which they live and move and have their being. Thus when human nature is referred to, it signifies the conditions of existence relating to the human race. The angelic nature is in a higher and different sphere of existence than that of humanity. (Psalm 8)   

As there is a vast difference between the conditions of existence of a fish and a bird, so we may reasonably suppose there is just as wide a difference between the human and angelic. The Divine nature is the highest of all natures, and is different from all others in this regard–it possesses inherent life and is, therefore, immortal. Whereas all other natures possess life that is not inherent, but is sustained by partaking of the life-giving elements peculiar to the different natures. 

A blending of natures would be a hybrid thing–a monstrosity. The Lord Jesus experienced two changes of nature— from spiritual to human (Hebrews 2:16,17) and then from human to Divine. It is promised in the Scriptures that the faithful followers of Christ shall also experience a change of nature, and will "became partakers of the Divine nature"- -the nature of God. 2 Peter 1:4.