Doesn't really apply to Manchester yet, but I suppose a smaller plane seven days a week is better than a larger one four days a week.
I think the point is, it appears they could easily fill a daily B77W on MAN-HKG.
The A350 will only take over once the flights go to daily. There is a schedule at work for 8 weekly at the moment, so, would be an overall increase.
Surely no-one knows yet, Cathay were quite conservative in returning to this market, the numbers appear to have pleasantly surprised some people.