Wasn't Rome also seasonal pre-pandemic?

I think it was year round but different frequency in different season. Barcelona was also year round by COVID as well I think.

It was daily in the summer and 4 weekly in the winter

Also hope Cathay will launch VIE and EDI.

I don't see EDI happening, especially before LGW or even Birmingham, though it would be amazing for me. Kind of surprised they haven't pushed into somewhere in Central/Eastern Europe as opposed to reopening seasonal tourist routes in the west but maybe their analysis shows right now that their fares are more affordable to vacationing HKers than Eastern Europeans and the business links aren't really there either.

how about DUB, SEA, HNL, CBR, ZAG, DOH, LAS, ATL, IAH ?

DUB - I think not ideal loads pre-Covid but a possibility for the future perhaps
SEA - faces bloodbath of competition from Taiwanese carriers now as noted many times in this thread
HNL - was the most popular unserved route from HKG in 2018 but there are doubts it still is / can compete with other, cheaper holiday destinations for HKers
CBR - too small plus both SYD and MEL are alternatives; CX isn't even back to Adelaide yet which would be the next logical Australian priority
ZAG - not sure why this would make sense before any other major city in Central/Eastern Europe, and if those cities are served, it probably wouldn't be. I would bet even on Belgrade over it given the Chinese traffic
DOH - makes the most sense from a Qatar connection perspective and has been served by CX before but Qatar does the route itself already so maybe not a priority until there's enough traffic
LAS - there has been speculation but I don't see it being a priority with Macau in HK's backyard
ATL - as a Delta hub rather than OneWorld it's unlikely; I would put my money on MIA in that region (AA hub, lots of Latin America connections, Swire real estate interests) if anything
IAH - don't think so; they just launched nearby DFW and Houston is a Star Alliance hub instead

i see a scneario where they could start flights to underserved (or even unserved) places by east asian carriers that definitely have demand, considering now cathays routes in Europe, NA, austraila etc. are extremely well covered

ATH, ADL, BHX, CPT, NCE, or other places in the middle east, africa that have plenty of east asian demand could be options.

or maybe increasing destinations that do not have daily service right now to daily if they're doing well, that seems to be what cathay is doing next summer to a lot of places in europe.

Would love to see them go back to MLE again, but perhaps will be something under UO in the future?

Would the type of person who is going to Maldives for vacation being willing to fly UO?

HX is already there plus BeOnd, the luxury Maldives carrier, is planning a route. Probably soaks up direct demand from both premium and non-premium passengers, although CX might be competitive for loyalty reasons. It would probably help if the HK economy were a bit better to stoke interest in lavish vacations there vs. the many cheap destinations available with a strong HKD right now.

There are still days in September not showing the ZRH flight. Does anyone know if they just havn't been loaded yet or if there are random days they aren't flying?

DOH is interesting. Many OW partners in the region are getting codeshare/transit business with QR through DOH, like AY BA JL MH, but CX seems to have no interest at all.

many budget airlines fly to maldives.

cx tried before and failed to maintain the route.