The 33% drop in Katowice passenger numbers in December is quite worrying - was there a reduced service or anything else that could have affected passenger numbers?
If it was due to Ryanair's Krakow flights stealing passengers (KRK is less than 50 miles away from KTW), then I wouldn't be surprised if the route was scrapped altogether. Maybe if Wizz operated to Belfast during the day time they'd have better fortunes; arriving in KTW at 01:35 isn't convenient in the slightest.