There are many books about making commerical games that are written by people that have not published a game. The books are still valuable in there content and guidelines.
Dan's book will be a valuable addition to the 3DGS community and if he gives some good common sense direction to get a game published thats pretty darn good.
There is no sure fire way to get your game published. Some recommended guidelines is all that is needed.
On the Physics issue, I agree with Newton you should cover both. You said it yourself the Newton Physics is well documented. Why do it again. The 3DGS version of physics could use a book authors help in getting the information out to us users. I would buy the book just for a good description of using 3DGS physics.
