Port numbers in the network layer?

During the development of TCP during the 1977-1980 period, the original 
C&K  TCP layer was divided into a transport layer (TCP) and an 
internetwork layer (IP). One of the key decisions in this split was 
which layer should inherit the port numbers. At the time I simply 
accepted the group decision to put ports into the transport layer 
without taking time to think through the architectural implications. Has 
anyone ever thought through how the architecture would have been changed 
had ports ended up in the internetwork layer, i.e., in IP?

Bob Braden