Hi Annie,

Think your sponsor doesn't understand what a target operating model is. Its basically a future state for the business. Solutions / projects etc come after the model has been defined and agreed. You need the As-is model in order to identify the gaps and to identify where you need to look for solutions to fill the gaps. 

This is basically business architecture. Good opportunity for you to broaden your skillset. Check out TOGAF online (think 9.0 is the current one) to see business architecture's place in enterprise architecture. If you are an IIBA member there are books on Bus Arch in their online library.

You're on the right track. Sounds like you need more ammunition to use against the sponsor.

Kimbo