For TATL, UA has left Eastern Europe to its alliance partners, relying either on connections through FRA/MUC/ZRH, or non-stops like ORD-WAW on LO. I don't know how friendly UA is with LO at the C-suite level, but the times I've tried the LO web site, it doesn't offer much outside of the Lot network, and I almost never see reward tickets on LO (but YMMV). Given the demographics in Chicago, I would expect ORD-WAW to support year-round service if UA offered it, especially if they figured out how to support booking onward connections on LO. I could also see encroaching on non-*A TATL destinations like ORD-PRG and ORD-BUD.