I live near Ealing and it's been a tremendous improvement to my commute. You're correct, fast intercity services and the stopping crossrail services likely can

I live near Ealing and it's been a tremendous improvement to my commute. You're correct, fast intercity services and the stopping crossrail services likely cannot coexist. But technically it is possible, assuming the requisite signalling standards are met by the rolling stock intended to be used. It's possible that only the Class 345 and Thameslink's Class 700's can meet this requirement currently.