Gdansk and Katowice were operated by Centralwings who folded in '09, they also flew to Warsaw, Ryanair went to Krakow and Lodz, so little to do with Wizz in reality.
Centralwings pulled their operations from Ireland in April '08. Ryanair operated from Shannon to Gdansk, Katowice, Krakow, Lodz and Wroclaw. They axed Gdansk and Katowice very early after they started, the market in Munster most definitely was flying ex-Cork. Krakow, Lodz and Wroclaw remained for a while thereafter, Wroclaw still remains. The Gdansk and Katowice routes ex-Shannon flopped because the successful Wizz operation on those routes at Cork, most definitely. There is a much larger catchment of Poles nearer to Cork, so I think it had a lot to do with the market preferring to fly from Cork.
This is why when Wizz are ending these routes and most probably eventually pull out of the ROI they wont be looking at Shannon.