Perhaps Crossrail should be seen as a sort of enhanced Central Line. One of tricks used by Paddington commuters in past years was to walk to Lancaster Gate, this took you to Central Line destinations without having to use the Bakerloo and change at Oxford Circus. As I understand it, the Crossrail station will be in Eastbourne Terrace. So if non-stops from Reading, Maidenhead and Slough survive, the fastest route is going to be to terminate at Paddington and change to Crossrail there.
It remains to be seen how or whether the Oyster system will be modified. Currently the limit is West Drayton.