I think for a couple of reasons - firstly the value of our shirt front has risen substantially and will rise substantially again if we're in the Champions league next season, that means that a new deal would be enough for us to pay out BK8 and still make more money, if the figures are right, it becomes a big possibility. And secondly because it's not entirely clear what's happening with the illegal Chinese gambling market and the slightly shady legality of advertising for it in the UK, and because the head of Suncity and presumed owner of TGP Group who own the BK8 brand (and pretty much all the other Premier league gambling brands) has been jailed for eighteen years on racketeering charges, the future of BK8 is a little unclear.
It's by no means certain that we will change shirt sponsors in the summer, but I wouldn't bet against it.