President Kaczyński has recently cast doubt on whether the euro would survive in the long run.
Such doubts have been voiced by many. It doesn't show anything, whether a person saying positive or negative about Euro can be supporter of Euro or not. His words maybe were just a response, a message to someones at top levels in EU rather than the public.
Euro's main problem is it is money of a union, but, not everybody joined it. UK, Poland, etc etc. Especially, UK is important there cause you're an important member, but, you aren't joining Euro. So, if Euro resists, Sterling goes away or UK exists EU. Otherwise, Euro collapse and Europe return to old days.