More than 75,000 passengers fly between Ireland and China in 2010 and Air China recently opened a ticket sales office in Dublin. About 1,800 passengers Ireland - China weekly.
That's 205 per day on average on the year figure, 257 on the weekly. No breakdown on FJY. Do the maths, to fill an A330-200 on DUB-PEK work you would need ~ 100% of the current market. Also given that a direct flight attracts a premium and that there are many good options on cheaper connecting flights, I don't see a business case given tough times and a price sensitive market.
There is no split between final destinations of PEK or PDG for instance. Lots of people flying to Beijing won't connect in Shanghai and vice versa. They will continue to use AMS, FRA, CDG and LHR on a one stop to final destination. Some of those travellers are very loyal at collecting points and like the familiar product, you won't shift them easily.
Hence you won't get close to 100% of the exisiting Ireland-China market and you can't make money without reaching that figure.
Final point, Air China still only operate the A332 on LHR-PEK, down from the B744 of years gone by, with China Southern just back on PHR-PDG after taking some time off. It's not a goldmine just yet.