No need for an Aer Lingus Regional service to DUB for transatlantic connections because Aer Lingus already offer connections to 13 USA/Canada destinations using the Flybe SOU-DUB services. They are for sale not on the Flybe website but on the Aer Lingus website for which purpose they carry EI flight codes.
This is not a new arrangement. I don't know when it started but I think it was at least two years ago.