simon not to return this year, there were rumours that simon cowell would come back to the uk judging panel, but he has now denied this, and the denials are recent, simon was asked at the auditions for bgt if you he would be returning to the uk judging panel this year, and he shook his head.
so that is one judge who will not be on the uk judging panel, so far only louis looks likely, another other judges for this year are not known, gary has left the judging panel, and it looks like all the other judges will be changed except for louis.
so simon is judging this years bgt, which he said he was not going to be returning to judging again this year, and so, if that was applied to the x factor judging panel maybe, you cannot take it so serious when he says he will not be back this year just yet.
if anything they always say one things and do another, so it could be a ruse saying he will not judge this year, then appear at the last minute as a judge, though of course judging both the uk and usa shows, there was talk that he would change the start dates so he could judge both shows, but that does not look to have happened either
so i would say wait and see closer to the time to see just who is judging the uk x factor, because there are always lots of rumours, but they purposefully keep it all secret until the last minute before the start.