Not completely out of left field ...
Long time reader, first post.
I was watching the anime again last night, specifically #72. In it, Orochimaru mentions why he wants to live forever (or really long time anyway). He says:
"I want to master all techniques, and understand the truth of this world. The one who mixed blue and yellow for the first time called the new color green. I want to do something similar to that. If blue represents chakra, yellow represents seals, and green represents the technique. As there are many different colors, there are tens of thousands of techniques in this world."
This seems to tie very heavily back into different natured chakra now. Granted he said blue represents chakra and yellow represents seals, not different elements.
Also wouldn't that mean that he would need to posses a body with a blodline limit that was capable of handling each combination? With Sharingan it seems he could copy the technique, but until he was in a body with that particular bloodline "capacity" I don't think he could truly do the technique.
Just wanted to throw this thought out there because I had read some stuff about this being completely out of the blue and I agreed at first. After watching these old episodes though it seems like Kishi really did have a plan the whole time.
Will