I think ITIL misses the point here. The concept of shared vs. internal is strange. When did corporations have non-shared IT service providers? I have been in IT since early 1980′s and I do NOT remember seen such things as a normal situation. The only cases have been loose corporations where the management has been in the process of restructuring the company and integrating It made no sense.
Shared vs outsourcing is too rough, there are so many types of sourcing. One popular model has been incorporating IT, creating IT Inc, which has (mainly) one customer. Then there are all these partial outsourcings which may leave the internal IT as a service integrator role. Service providers may provide application services, desktop infrastructure, servers, networking etc. ITIL does not really understand these different roles.
The latest move is about business buying it services without IT. This is completely different from IT doing outsourcing.
