I know much has been already speculated concerning the V8 returning to F1. Honda's version is fast right out of the box, I would assume all versions will be lighter and more fuel efficient. It's certain that we will get more than a few surprises; there is much speculation already that the Japanese manufacturers may reign and will be tough to beat. After reading the following article, it got me to thinking that the V8 engine rule will change F1 in many ways:
http://www.grandprix.com/ns/ns14730.html