If you look back in the forum, you’ll see that there has been some issues with LOT’s long haul fleet. I wouldn’t say at the moment that it’s unlikely to be operated because the situation can change unexpectedly, but if you’re worried, then use a different carrier out of BUD to ORD and back if the times are similar. Unless you want to wait until two weeks before and risk a much higher fare to verify that the flights are confirmed.

i’ve had it recently where a flight was cancelled because of a management decision in the future and it’s a trip that had already been confirmed. Nobody said anything to me that it might happen or anything like that because it was likely to be operated at the time. There’s always some risk when you fly that the flight is delayed or cancelled.

Do you know when those flights were cancelled? If not, then there’s no reason to doubt that it’ll not be operated but if you would rather fly with another carrier, then you have Austrian via Vienna, British Airways via London Heathrow and Lufthansa via either Frankfurti or Munich. As I said just above, there’s always a certain risk on your time when you fly and if there’s an issue then see what they offer you or seek a refund and make your own alternative arrangements.