What happens if you use Excel 2013 or later and upgrade the Data Models accordingly, but SharePoint is still 2010? Now your client applications and workbook Data Models are ahead of your server applications. The server software in SharePoint Server 2010 will not recognize the Data Model the same way. SharePoint Server 2010 uses Analysis Services client libraries and Power Pivot Web Service to redirect data load and query requests to Analysis Services. Those client libraries and Web service will not come into play if the Data Model is Excel 2013 or later . The workbook will open in the browser, but if you click a slicer or filter that sends a query to the Data model, you’ll get the error about the workbook containing an unsupported Power Pivot model.
If you’re not upgrading to SharePoint 2013 right away, you might want to dig up that previous version of the workbook and use Excel 2010 and a Power Pivot add-in to maintain the Data Model.
Alternatively, you can use Office 365 to store the workbook. Office 365 supports loading and querying Data Models without Power Pivot for SharePoint. Microsoft Data Centers provide behind the scenes support for hosting Data Models that are embedded in Excel 2013 workbooks.