Because we are led to believe Cardiff is out of contract, the crowds are around 50% down on their peak, all the other big stadium SGP's have gone with the exception of Warsaw, Belle Vue have openly said they're after a GP, WBD gave them the SoN to prove they could stage a GP and it wouldn't be the first time a GP has been announced but then failed to materialise... and there's still no date been announced, which doesn't usually happen. You don't have to be a genius to read between the lines