Your approach perfectly makes sense.
Call it "Enterprise Data Architecture", call it "Enterprise Information Map" - it is indispensable to get ready for the future. In any medium and large organization, (almost) all operational units create, update, use and interpret data for the major part of their daily business duties (even where tangible goods are produced using machines, the latter ones are data-driven.) Consequently, medium and large organizations are first and foremost in "information business" (whereas the underlying data model may vary depending on the industry).
An Enterprise Information Map is therefore not only helping the CIO to develop a road map from a siloed to an integrated application landscape, but should primarily serve as a blueprint for the CEO (with "E" as in "Executive") to pursue the alignment of the operational business units with the "new reality" of being an information business. The CEO should assume leadership in this alignment process, nominate responsible parties and monitor progress and results closely.
In a nutshell, the alignment includes (but is not limited to) business (not IT!) activities such as:
- Design the Master Data model as the core piece of the Enterprise Information Map
- Assign ownership of information entities to business units
- Identify "central" information entities without "natural" owner (such as master entities Party and Location as well as reference data) to a (new) central unit responsible to conceive mechanisms for management and governance of "central" information entities and to license the above mechanisms for reuse in decentral business units
- Nominate data stewards in decentral business units that are responsible to reuse central mechanisms and, based on entity ownership, to conceive decentral measures for data governance
- Reorganize business processes based on the above mechanisms as well as to integrate data governance measures
- Restructure existing business units to support the reorganized processes
- Train managers and staff how to support the "new" culture.
The above is only a primer to answer your initial question within the given limitations of this medium. Therefore, please feel free to follow up or contact me directly.
I'd like to emphasize here, though, the importance of the CEO's commitment to make sure that the investment into an Enterprise Information Map pays off and will not only remain a sandbox game.