Keep in mind that what you see on that Draft is just for the "small language", which is being worked on by the "Working Group 1". Then there is "Working Group 2" which is going to take care of building a standard library of non-core features. This means that R7RS in it's whole is going to be more than R5.1 -- but the separation is needed imo is wide adoption is desired.

You can get more information here: http://scheme-reports.org/