To be honest, it looks like a bit of a disaster
Stobart now have to find "up to 18 new routes" for which they don't seem to have any a/c.
They could look to play around with their current ATR's to create some capacity, but the sort of routes they can service haven't proved to be a huge success in the past.
If they go for jets they have to buy at short notice (from where? those 146's are parked up for a reason) with all the costs of a new type and crewing etc or lease in - so BE take a cut and the operator takes a cut, so how much does that leave Stobart?
On the other hand, CityJet are left with a fleet of new jets, and no apparent focus. Moving away from SEN, the Aer Lingus Regional model looks a good one and the SSJ would have slotted in nicely between the Atr's and EI's Airbuses. Wouldn't have done the SSJ and CityJet any harm to have a solid customer like EI, either. Not saying that won't happen, but would have worked better.
Hopefully both parties have "plan B" in place and they come off.