I don't think there will be any significant change to StobartAir flights, EI Regional has worked very well against FR into the UK regional airports and helped in building a strong hub for EI at Dublin. I don't see why the formula, much less the brand would change. IB retain their IBRegional operation.
I doubt handling at DUB will be outsourced, what could happen is that IB, BA and possibly AA flights are handled by EI, not sure about Vueling.