If Dublin is to be turned into a hub, it will be one for passengers heading from Europe to the US and Canada, so the sooner the bilateral can be sorted out, the better.
Dublin will never be a hub, given that its terminal layout doesn't meet the minimum requirements for connecting passengers and that its only based carrier with long haul equipment- Aer Lingus, is rapidly becoming a point-to-point operator, with no strategy in place to co-ordinate long haul/short haul schedules.
Shannon does have a suitable terminal layout but is unlikely to attract a based carrier.