Full payload A320 operations from SEN to Polish destinations should be entirely feasible.
Although that statement is based on study of material from the Airbus website, and I fully acknowledge the potential pitfalls of this method, some corroboration is available elsewhere from a recent report that an A320 operator had studied A320 performance from SEN and concluded that AGP and FAO were viable destinations.. As always, welcome comment anyone with more authentic information.
Straight line distances from SEN are: FAO 948nm, AGP 921nm, WAW 749nm, Lublin LUZ (furthest likely Polish destination) 820nm.
Of course Polish routes would be a good fit for SEN insofar as EZY is not a major player in the Polish market. Would Wizzair really want to move part of their operation and how keen would SEN be to have them ? They seem to have a reputation that rivals Ryanair's, whether deserved or not I do not know. And this is all just a speculation with no basis in reality I think ?
There is a good case for saying that the development of domestic routes from SEN would be better served by smaller aircraft operating at greater frequency than is likely with an A319. If the business case is strong then sooner or later someone will pick it up. For whatever reason, Flybe turned their backs on SEN. I don’t think we should be too concerned at their absence.