Is there a way to use the Evolution address book as a data source
Address book integration is Mozilla's responsibility.
Mozilla supplies functionality to access the address book and LibreOffice has certain (slightly modified) functions made up of Mozilla's and a bridge between the Mozilla XPCOM-API and LibreOffice's UNO-API. Check the relevant part of the Mozilla website for more information.
The question should be, does Mozilla envisage supporting the Evolution address book as a data source? We are working with the Mozilla developers on the address book, however it is not possible for us to give an answer on this subject. Nevertheless, it is certainly something to think about!