And you were fortunate that you were able to leave the airport!
I was on a QR flight a couple of weeks earlier than yours, missed my connection QR (J class) and QR did not provide a hotel voucher, visa (luckily I have dual citizenship and was abel to exit the airport after paying the visa fees), or inf. It took 5+ hours to know on what flight I was on (24 hour delay)… I had to book a hotel on my own ($500) and arrange for transportation.
Mind all flights were on one record and with QR. After 2 hours we were allowed to wait in the lounge. The lines at the transfer desk were long with no priority whatsoever and people screaming and booing, even the following day there were long lines with unhappy campers…

In paragraph 61, the Court finds that “passengers whose flights are delayed may rely on the right to compensation laid down in Article 7 of Regulation No 261/2004 where they suffer, on account of such flights, a loss of time equal to or in excess of three hours, that is to say when they reach their final destination three hours or more after the arrival time originally scheduled by the air carrier. ”

Apart from the fact they create an equal protection between cancellation and delay, it is also important to note that they use the term “final destination”. This means, when reading art. 2(H) of 261/2004, that is is irrelevant whether or not the journey to the final destination is made non-stop or through connecting flights. You’ll fall within the scope of the Regulation as long as you’re traveling on a through ticket departing from the EU. In the eyes of the EU, you are not travelling Brussels – Doha and Doha- Hong Kong, but Brussels – Hong Kong.

This is, of course, as long as you are on a trough ticket.. Otherwise, bad luck.

I was in touch with Cathay Pacific after the delay (I made a complaint using their website link). They offered me 2 upgrade vouchers for a future flight, that can only be used at check-in when a seat in a higher class is available. EU’s Regulation EC261 for financial compensation does not count since the flight did not originate from a EU city (although the ticketed itinerary did). My colleague, who joined me on this trip in business class and who is also a Oneworld Emerald member, wrote the exact same letter to Cathay Pacific, and he was given a 100 Hong Kong dollar voucher to be used for a future flight.