Crossrail will almost certainly be a TfL concession like LO, and Abellio have been told to separate their Shenfield Metro route into a business unit capable of being transferred lock stock and barrel to Crossrail by the end of this short franchise. (i.e. all relevant train crew, managers, station staff and maintainers to form a separate 'mini TOC'. I guess that means no-one will be diagrammed on any other routes?)
However, the Crossrail concessionaire will be awarded competitively, so the Shenfield Metro 'business unit' could just as easily find that the same company who runs the Greater Anglia franchise at the time happens to win Crossrail anyway...