Evan Weiner over at the Daily Caller also ponders a realignment plan involving three divisions. His perspective is somewhat different than mine - an 8-8-14 split instead of 10-10-10 and no promotion/relegation aspect, but it's good to see someone else thinking along the same lines.
I will have three more parts to my realignment plan in the coming days. Opening Day is about two weeks away, so I'll try to get back into writing more.
EDIT: Didn't read closely enough. He does suggest some promotion/relegation aspects. Just read the whole article more closely than I did.