I'm sure there has been no declaration from Stobart that they will not launch additional routes from SEN under the Stobart Air/Flybe brand; it would be a pretty daft thing for them to say wouldn't it?. Neither have I heard any whispers to that effect.
There is obviously a limited number of opportunities in terms of potential routes but if, say, just two or three of the existing four routes proves sustainable in the medium term I would be surprised if replacements were not sought to ensure full utilisation of the SEN-based airframe. DUB would surely be on that list for future reinstatement I would think.