This is also a question that I have previously posed, and I too would love to know if (and I'm sure there are) there are any more reliable sources RE. Cathay's route resumptions. They are still intent on aiming for 100% pre-pandemic capacity towards the end of this year, and already, progress has been made in terms of restoring capacity on key routes (e.g. LHR), as well as the reopening of "thinner" long haul routes (e.g. BCN). Based on current hinting, I think the following are most likely to be resumed by Cathay Pacific in the near future:

LGW- particularly with LHR having been restored to 5 daily, and as previously mentioned, has been hinted extensively on here and elsewhere. Rumoured to be returning in October, 5 weekly with the A350-900. I also think that the recent announcement of SQ coming to LGW is fuelling their return so that they can compete against SQ from LGW for transit passengers, similarly to how the two carriers compete at LHR.

FCO- served for many years prior to being suspended.